8A Food, glorious food!...(L7) Describe how nutrients are supplied to cells via the blood and tissue...

Exploring Science edition © Pearson Education Limited 200826

8Aa

This unit covers diet, digestion and the transport of and uses for the nutrients in digested food. All of this is looked at within a context of food advertising (including diets and supplements).

We recommend between 8 and 11 hours of teaching time for this unit.

From KS2/previous units most pupils will:• understand that foods contain a variety of substances needed by

the body and recognise the idea of nutrition as a life process• appreciate that a wide variety of foods needs to be eaten to have

a balanced diet• know that food contains stored energy• be familiar with the names and positions of some of the organs in

the digestive system• know that substances are carried around the body by the blood –

the idea and process of absorption will be unfamiliar to most.• be familiar with respiration as one of the life processes.

This unit builds on ideas introduced in the QCA Scheme of Work for KS2: Unit 5A Keeping healthy. It also builds on work covered in Unit 7A Tissues and transplants and 7G What a waste!

The unit starts by looking at food advertising and the laws governing it. The components that are found in food are then covered, revising material from KS2 before going on to look at food tests and balanced diets. Digestion is then covered, including the role of enzymes.

Respiration is mentioned at the end of this unit and is covered in detail in Unit 8B. The latter looks at how oxygen is provided to cells for respiration, whilst this unit looks at how glucose is provided. The circulatory system is covered briefl y in this unit and in more detail in Unit 8B.

• Topic 8Aa starts by introducing the idea that health experts are worried about the effects of unhealthy diets on children, and the role that advertising plays in this. There is revision of what a diet is and the various food substances found in foods, including how to test for them. There is Could level material on the recommended daily intakes of different food substances.

• Topic 8Ab extends knowledge from 8Aa, considering the ideas of a balanced diet, the components of food and their uses, and the energy content of foods. There is Could level material on diseases and disorders that require special diets.

• Topic 8Ac covers digestion, the organs involved and the role of enzymes. Could level material covers teeth, extending ideas that pupils will have met in KS2.

• Topic 8Ad considers enzyme activity in more detail. There is an optional investigation for Attainment Target 1 on amylase activity. A set of level descriptions is provided in the ASP. Could level work covers the roles of the liver and pancreas in digestion.

• Topic 8Ae looks at the absorption of digested food in the small intestine and how the food substances are transported around the body to where they are required.

ExpectationsKey concepts At the end of this unit…All pupils must: (L4) Explain why food manufacturers use health slogans.(L5) Use a model to describe the action of enzymes.

Most pupils should: (L5) Recognise that scientifi c knowledge is sketchy in some areas and therefore drawing conclusions is diffi cult.(L6) Decide whether manufacturers are right to put certain claims on their food labels.(L6) Use models to represent the digestion of large insoluble food molecules.

Some pupils could: (L7) Explain why it is diffi cult to interpret some scientifi c facts.(L8) Describe the tests for water, protein, glucose and sucrose.

Key processes At the end of this unit…All pupils must: (WTL4) Display data in tables.(WTL4) Control variables appropriately, with help.(L4) Use data from secondary sources of information to construct bar charts.(L5) Without help, point out that variables need to be kept the same in investigations and stop these variables changing.

Most pupils should: (L4) Identify and control variables appropriately without help.(L5) Carry out and interpret results from tests for starch and fat.(L6) Display data in a variety of different forms.

Some pupils could: (L7) Explain what food allergies and intolerances are.(L8) Use own initiative to independently research and obtain secondary information from secondary sources.

Range and contentAt the end of this unit…All pupils must: (L4) Recall the names of the major nutrients in food and good sources of these substances.(L5) Describe what a balanced diet is.(L5) Describe how digested food is transported around the body.

Most pupils should: (L5) Recall that nutrients, fi bre and water are all vital components of a balanced diet and good sources of these substances.(L5) Recall the roles of nutrients, fi bre and water in the body.(L6) Describe how nutrients are digested and absorbed.(L7) Describe how nutrients are supplied to cells via the blood and tissue fl uid.

Some pupils could:(L8) Explain why some food cannot be digested by humans.

Be prepared8Aa Starter 3, 8Ab Exploring 3, 8Ab Explaining 3 and 8Ae Exploring 2 require advert cuttings, food packaging and/or scientifi c media reports about food.8Aa Exploring 2 and 8Ab Exploring 1 require nutrition information panels cut from various food packets.8Ab Explaining 5 requires a visit from a nutritionist.8Ac Explaining 3 requires a bicycle inner tube, stone, tennis ball, sock, sheep lungs and oesophagus.8Ae Explaining 2 requires glucose monophosphate solution and starch phosphorylase (or raw potato).

For a list of updated and vetted websites that can be used to support your teaching of this unit please visit the Exploring Science: How Science Works E-Forum (http://groups.google.co.uk/group/exploringscience).

8A Food, glorious food!

8A

M01_TTPG_5453_U0_5p.indd 26 12/9/08 12:24:38

© Pearson Education Limited 2008 27Exploring Science edition

8Aa

8A NC statements coveredFrom KS2

Statement TopicSc2 1a That the life processes common to humans and

other animals include nutrition, movement, growth and reproduction.

all

Sc2 2a About the functions and care of teeth. 8AcSc2 2b About the need for food for activity and growth,

and about the importance of an adequate and varied diet for health.

8Aa, 8Ab, 8Ae

Sc2 2c That the heart acts as a pump to circulate blood through vessels around the body, including through the lungs.

8Aa, 8Ab, 8Ae

At KS31 Key concepts

Statement Topic1a Using scientifi c ideas and models to explain

phenomena and developing them creatively to generate and test theories.

8Aa, 8Ac, 8Ad, 8Ae

1b Critically analysing and evaluating evidence from observations and experiments.

8Aa, 8Ab, 8Ad

2a Exploring how the creative application of scientifi c ideas can bring about technological developments and consequent changes in the way people think and behave.

8Ac

2b Examining the ethical and moral implications of using and applying science.

8Aa, 8Ab, 8Ae

3a Recognising that modern science has its roots in many different societies and cultures, and draws on a variety of valid approaches to scientifi c practice.

8Ab

4a Sharing developments and common understanding across disciplines and boundaries.

8Aa

2 Key processes

Statement Topic1a Use a range of scientifi c methods and techniques

to develop and test ideas and explanations.all

1b Assess risk and work safely in the laboratory, fi eld and workplace.

8Ab, 8Ad

1c Plan and carry out practical and investigative activities, both individually and in groups.

8Aa, 8Ab, 8Ac, 8Ad

2a Obtain, record and analyse data from a wide range of primary and secondary sources, including ICT sources, and use their fi ndings to provide evidence for scientifi c explanations.

8Aa, 8Ab, 8Ad, 8Ae

2b Evaluate scientifi c evidence and working methods.

8Ab, 8Ad

3a Use appropriate methods, including ICT, to communicate scientifi c information and contribute to presentations and discussions about scientifi c issues.

8Aa, 8Ab, 8Ad, 8Ae

3 Range and content

Statement Topic2b Elements consist of atoms that combine together

in chemical reactions to form compounds.8Ae

3a Life processes are supported by the organisation of cells into tissues, organs and body systems.

8Ac, 8Ad, 8Ae

3c Conception, growth, development, behaviour and health can be affected by diet, drugs and disease.

all

3e Behaviour is infl uenced by internal and external factors and can be investigated and measured.

8Aa, 8Ab, 8Ad

4 Curriculum opportunities

Statement Topica Research, experiment, discuss and develop

arguments.all

b Pursue an independent enquiry into an aspect of science of personal interest.

8Ab, 8Ac

c Use real-life examples as a basis for fi nding out about science.

8Aa, 8Ab, 8Ad, 8Ae

d Study science in local, national and global contexts, and appreciate the connections between these.

8Ab

e Experience science outside the school environment, including in the workplace, where possible.

8Aa, 8Ab

f Use creativity and innovation in science, and appreciate their importance in enterprise.

8Ab, 8Ad

h Explore contemporary and historical scientifi c developments and how they have been communicated.

8Ab

i Prepare to specialise in a range of science subjects at key stage 4 and consider career opportunities both within science and in other areas that are provided by science qualifi cations.

8Aa, 8Ab, 8Ad

j Consider how knowledge and understanding of science informs personal and collective decisions, including those on substance abuse and sexual health.

8Aa, 8Ab, 8Ae

k Make links between science and other subjects and areas of the curriculum.

8Aa, 8Ae

Links with other units

7A Nutrition and respiration as ‘life processes’. The concept of things being adapted to their functions. Cells, tissues, organs and organ systems.

8C Important microbes in food manufacture (e.g. baking). Anaerobic respiration.

7B The test for starch. Feeding babies.

8E The words dissolve, solvent, soluble, insoluble. Filtration.

7C Food as a source of energy. 8G Molecules7E Acid in the human

digestive system. 9B Food for health.

7G The particle model of matter.

9C Plants for food. Starch.

7I Food as a source of chemical energy.

9I Energy wasted as heat.

8B Transport of carbon dioxide and oxygen in the bloodstream. Respiration.

Cross-curricular links

Topic Links8Aa Food technology/PSHEE – healthy eating.

Citizenship – media and advertising.D&T – new foods.

8Ab Food technology/PSHEE – healthy eating.Citizenship – respecting differences (in diets).D&T – new foods.Geography – food around the world and food supply problems.

8Ac PSHEE – tooth decay.Citizenship – advertising claims.

8Ae Citizenship – advertising claims.Food technology/PSHEE – healthy eating.

Skills opportunities for Personal, Learning and Thinking Skills (PLTS), literacy, numeracy and ICT are included in the individual topic notes.

Food, glorious food! 8A

8A

M01_TTPG_5453_U0_5p.indd 27 12/9/08 12:24:38


Framework statements covered by Unit 8A

1 How Science Works

1.1 Explanations, arguments and decisions

Code Framework threads Year 8 Topic1.1a1 Scientifi c thinking: developing

explanations using ideas and models

Describe more than one model to explain the same phenomenon and discuss the strengths and weaknesses of each model.

8Ac, 8Ad

Describe how the use of a particular model or analogy supports an explanation.

8Ac, 8Ad

1.1a2 Scientifi c thinking: challenge and collaboration in the development of explanations

Recognise that science is a communal, and therefore fallible, human activity and that different explanations can arise from individual bias.

8Ab

Recognise questions that the scientifi c process cannot yet answer. 8Ab1.1a3 Scientifi c thinking: developing

argumentIdentify a range of scientifi c data and other evidence to back an argument and the counterclaim in more complex and/or less familiar contexts e.g. use of antibiotics.

8Ab, 8Ac

Describe how scientifi c evidence from different sources carries different weight in supporting or disproving theories.

8Ab

1.1b Applications, implications and cultural understanding

Explain some issues, benefi ts and drawbacks of scientifi c developments with which they are familiar.

8Ab, 8Ac, 8Ad, 8Ae

Recognise that decisions about the use and application of science and technology are infl uenced by society and individuals, and how these could impact on people and the environment.

8Aa, 8Ab, 8Ae

1.1c Communication for audience and with purpose

Use a range of scientifi c vocabulary and terminology consistently in discussions and written work.

all

Adapt the stylistic conventions of a range of genres for different audiences and purposes in scientifi c writing.

8Aa, 8Ab, 8Ae

1.2 Practical and enquiry skills

Code Framework threads Year 8 Topic1.2a Using investigative approaches:

planning an approachDescribe an appropriate approach to answer a scientifi c question using sources of evidence and, where appropriate, making relevant observations or measurements using appropriate apparatus.

8Aa, 8Ad

1.2b Using investigative approaches: selecting and managing variables

Describe and identify key variables in an investigation and assign appropriate values to these.

8Ad

1.2c Using investigative approaches: assessing risk and working safely

Explain how to take action to control the risks to themselves and others, and demonstrate competence in their practical techniques.

8Aa, 8Ad

1.2d Using investigative approaches: obtaining and presenting primary evidence

Explain how the observation and recording methods are appropriate to the task.

8Ab, 8Ad

Describe ways in which the presentation of experimental results through the routine use of tables, charts and line graphs makes it easier to see patterns and trends.

8Aa, 8Ab

1.2e Working critically with primary evidence

Describe how the patterns and trends in the results link to the conclusions drawn and whether the evidence is suffi cient.

8Ad

Describe and suggest, with reasons, how planning and implementation could be improved.

8Ad

1.2f Working critically with secondary evidence

Describe what needs to be considered in the collection and manipulation of simple secondary evidence to evaluate the conclusion or interpretation made.

8Ad

2 Organisms, behaviour and health

Code Framework sub-strands Year 8 Topic2.1 Life processes Explain how the organs and tissues in plants and animals function to support

the seven life processes in a healthy organism.8Aa, 8Ac, 8Ad, 8Ae

2.2 Variation and interdependence Explain how variation has benefi ts and limitations for the survival of organisms in specifi c habitats.

8Aa

2.3 Behaviour Explain how changes in learned behaviour due to internal and external stimuli are of benefi t to the organism.

8Aa, 8Ae


8A

M01_TTPG_5453_U0_5p.indd 28 12/9/08 12:24:38


Food, glorious food! 8A

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8A

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8A Background information8Aa – Advertising food/On a dietThe word diet is most often used in the context of ‘going on a diet’ to lose body mass. Pupils need to understand that a diet means ‘what you eat’. A healthy diet should provide the fi ve nutrients (proteins, fats, carbohydrates, minerals and vitamins), fi bre and water.

Fibre mainly consists of plant cell wall material (cellulose), which humans do not have the ability to digest. Herbivorous animals use bacteria in their guts to digest this material. Herbivores tend to have longer guts than carnivores or omnivores to help with this process. Muscles in the wall of the gut squeeze the gut to push food along. This squeezing is called peristalsis. Fibre adds bulk to the food, thus aiding this process. A lack of fi bre can cause a lack of solid material for the muscles to push against and the food to move very slowly, resulting in constipation.

Water is also an important component of the diet. It is used to carry dissolved chemicals around the body and most biochemical reactions do not occur without the reactants being dissolved in water. It is also used as a lubricant.

Nutritional information labels should be familiar to most pupils from daily life. It should be noted that these nutritional contents are all mean (average) values.

To make ‘fair’ comparisons between foods, the content in 100 g of each food is examined. The contents do not always add up to 100 g since water is very often not mentioned on the labels.

8Ab – Keeping it balanced/Poor diets/Focus on: Diabetes and dietA balanced diet is one that contains a wide variety of foods. Many foods contain carbohydrates, proteins and fats, but may be lacking in some of the essential vitamins and mineral salts. It is also important to eat protein from a wide variety of different sources, since different proteins contain different amino acids.

Carbohydrates are used for energy and consist of the elements carbon, hydrogen and oxygen. They can best be classifi ed into two groups – those containing small molecules (sugars) and those containing sugars linked together to form long molecular chains. One of the best known examples of the latter is starch and that is the only long chain (or complex) carbohydrate that is considered in this unit. There are a whole variety of other complex carbohydrates including cellulose. Cellulose should not be mentioned to pupils in this context since it is indigestible by humans and therefore has no energy value to humans. It is the major component of fi bre.

Most sugars are drawn as hexagons because of the way that the carbon atoms in the molecule join together. One of the simplest sugars is glucose – one hexagonal ring (a monosaccharide). Another monosaccharide is fructose (pupils may have heard that bananas contain a lot of this). Sucrose is basically two hexagonal sugars joined together (a disaccharide). The same is true for lactose and maltose. Pupils will know that too much sugar is bad for teeth and can make you fat. Eating too much carbohydrate increases body mass since any extra is turned into fat and stored.

Pupils often hold the misguided notion that all fat is bad for you. In fact, fat is a vital component of the diet (for example, it is one of the major components of cell membranes). Fats are also used as an energy store and as insulation under the skin. Fats also contain a store of some vitamins (see below). It should be emphasised that, whilst too much fat is not a good idea, we all need to eat some. A fat is basically a molecule of a chemical, called glycerol, which has three chains of fatty acids attached to it. It is composed of carbon, hydrogen and oxygen atoms. Animal fats tend to be saturated (they have as many hydrogen atoms as will possibly fi t onto the

chain). Eating too much saturated fat has been linked with the over-production of cholesterol (another fatty substance that can stick to artery walls, thus blocking them and causing heart disease). We do need some cholesterol in our diet (although it can be made by the liver) since it is a precursor of many other important compounds needed by the body (including some hormones). Vegetable fats are regarded as healthier since they do not contribute so readily to the over-production of cholesterol (they tend to be unsaturated – having some ‘empty gaps’ where hydrogen atoms could fi t).

Proteins are chemicals vital for growth. They form essential parts in cells and nearly all enzymes (chemicals that help biochemical reactions to occur – ‘biological catalysts’) are proteins. They consist of long chains of amino acids. These contain oxygen, carbon, hydrogen and nitrogen. The body breaks down proteins to their constituent amino acids, and then rebuilds them into new proteins. A defi ciency of protein causes a muscle-wasting disease called kwashiorkor.

Vitamins are compounds needed in small amounts. They are divided into two groups – fat-soluble vitamins and water-soluble ones. The former are vitamins A, D, E and K and all the rest are water-soluble. The fat-soluble ones can easily be stored in fat in the body. Some of the water-soluble ones (e.g. vitamin C) can also be stored to some extent. The two vitamins covered in the Pupil’s Book are A and C. Vitamin A is needed for good eyesight (especially in the dark). It also helps skin cells to develop and is needed for strong bone growth. Vitamin C is used to help form ‘connective tissue’, that is tissue that helps join other tissues together. A defi ciency over a period of about 6 months causes scurvy (a disease characterised by bodily weakness, bleeding gums and swollen, painful joints).

The elements carbon, hydrogen and oxygen are provided in most foods. Nitrogen is provided in proteins. Trace elements (e.g. calcium and iron) are those that, although vital, are needed in much smaller quantities. These trace elements are taken in the form of chemical compounds that make up organisms used as part of our food. Calcium is needed in the formation of bone. A defi ciency causes rickets. Iron is needed to make haemoglobin (the oxygen-carrying chemical in red blood cells). A defi ciency results in anaemia (reduced oxygen-carrying ability, resulting in shortness of breath and a lack of energy). What we tend to refer to as minerals are really mineral salts – that is compounds that contain an important element for our health. Calcium phosphate is a mineral salt. We tend to call this ‘calcium’ or ‘phosphorus’ depending on the context!

There are a huge range of terms used to recommend how much of each sort of food substance someone should eat. For many years the recommended daily allowance or RDA system used to suggest how much of a certain food substance you should eat. This system has generally been replaced by Guideline Daily Amounts (GDAs). GDAs are estimates of the amount of energy and nutrients needed by people in the UK, arranged into groups by age and sex. They take into account more types of data than the old RDAs.

There is also data available for Tolerable Upper Limits (TULs). This information can be important when people are eating very unbalanced diets or taking large amounts of supplements since some nutrients (e.g. vitamin A) have been demonstrated to be harmful above a certain level of intake.

Dieting is something that many teenagers become concerned about. Important points that should be stressed, in class discussion, are that people all have different body shapes and sizes, partly because of who we are (inherited causes) and partly because of what we eat (environmental causes). It is also true to say that many children will lose excess fat as they go through puberty (the excess fat can be thought of as an evolutionary adaptation, providing insulation and a ready supply of stored energy for young, more vulnerable humans until they can fend for themselves).


8A

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Junk food may, on fi rst inspection, appear to be fairly balanced. However, most of it contains very high levels of sugar and fat, and many essential vitamins and minerals are missing. Most of it is highly processed, which removes a great deal of the fi bre. One piece of lettuce and a tomato in a hamburger does not constitute a good supply of fi bre and vitamins!

Excess carbohydrates in the diet are converted into fat (both fats and carbohydrates are composed of carbon, hydrogen and oxygen atoms) and stored. Equally, if there is not enough carbohydrate in the diet, the fat will be reconverted into a form that can be used for respiration. In starvation, when fat stores have been used up, the body converts protein into a form that can be used in respiration. This can result in the body destroying its own muscles to release protein, leading to a wasting condition called marasmus.

8Ac – You’ve got gutsFor a full discussion on the roles of individual food components, see section 8Ab.

The parts of the digestive system that food goes through (apart from the mouth) are collectively known as the gut. The gut contains the gullet or ‘food pipe’ (also known as the oesophagus), stomach, small intestine (split into two parts – duodenum and ileum), large intestine (or colon), rectum and anus. For simplicity’s sake, the words in brackets are not used in the Pupil’s Book and do not need to be known. The rest of the digestive system consists of salivary glands, liver, gall bladder and the pancreas. Only the salivary glands and liver are referred to on page 14. The pancreas is mentioned on page 13 for more able pupils. The gall bladder is not covered (it stores bile).

Digestion occurs because most food is insoluble, and only soluble substances (for the most part) can be absorbed into the body.

Digestion starts in the mouth, where the salivary glands (a gland is an organ whose main function is to secrete specifi c chemicals), release saliva. This contains an enzyme. Enzymes can be imagined as ‘chemical scissors’, cutting up long molecules into shorter ones. The enzyme in saliva is called amylase and it chops up starch into a sugar (called maltose). A slight simplifi cation (that starch is turned into glucose directly) is implied in the Pupil’s Book and worksheets. The teeth help to grind the food, mixing it thoroughly with saliva and giving the amylase more surface area on which to work. The saliva also contains mucin, a sticky substance that holds the food together and lubricates it ready for swallowing. The lump of lubricated food is called a bolus. This passes down the gullet, moved by contractions of muscles (peristalsis).

The stomach wall secretes pepsin (which breaks down proteins into shorter chains called peptides) and hydrochloric acid (which kills bacteria and helps to ‘activate’ pepsin). Pupils often ask why, if the contents of the stomach are between pH 1 and 2, the stomach does not dissolve itself. This is because the stomach releases a sticky mucus that lines the stomach and prevents attack from the acid. Problems with mucus production can cause stomach ulcers. The stomach churns the food up into a liquid called chyme. The chyme is released slowly into the fi rst part of the small intestine (the duodenum).

Here, the acid from the stomach is neutralised by a constituent of bile, allowing enzymes secreted into the small intestine to work. Various enzymes are released by the wall of the small intestine and by the pancreas (another gland). These include maltase, which splits maltose into glucose, and peptidases, which split peptides into amino acids. Bile (a green liquid, produced by the liver) is released from the gall bladder. This forms an emulsion with fats, giving a suspension of small fat droplets and providing a greater surface area for lipase enzymes to get to work, splitting the fats into fatty acids and glycerol. The term glycerol is not mentioned in the Pupil’s Book.

8Ad – Break downFor information on digestion and digestive enzymes see 8Ac.

Each enzyme has an optimum pH and a temperature at which it works best. Pepsin has an optimum pH of about pH 2 and salivary amylase an optimum of about pH 7. In humans, the optimum temperature for most enzymes is body temperature (37 °C).

8Ae – In the blood/Health claimsThe absorption of digested food occurs in the small intestine. To ensure that this process happens quickly, the small intestine is highly folded and has fi nger-like projections, called villi, sticking out of it into the liquifi ed food. The cell membranes of the cells making up each villus are also highly folded, forming microvilli. The folds, villi and microvilli, all increase the surface area of the small intestine to ensure rapid absorption. In addition, the outer cells on the villi are thin, allowing substances to pass quickly through and into the capillaries inside.

Sugars and amino acids (from carbohydrate and protein digestion respectively) pass into a fi ne network of small blood vessels called capillaries inside the villi. At this level pupils do not need to understand how this happens and may be told that it happens by diffusion – small molecules happen to pass through the small intestine wall on their own (rather like a smell spreading through a room without anything having to move the ‘smell particles’). In fact absorption is more complex than this, with the cells on the surface of the villi actively picking up the digested food molecules and transporting them into the capillaries.

Not all digested food enters the bloodstream. The majority of glycerol and fatty acids (from the digestion of fats) enter a blind tube in the centre of each villus, called a lacteal. The lacteals empty their contents into the lymphatic system. This is a network of tubes that run throughout the body, eventually draining into the bloodstream.

Respiration is a cellular process that occurs in certain small compartments (organelles) in the cytoplasm called mitochondria. Many pupils make the mistake of saying that ‘energy’ is a product. This is not true since ‘energy’ is not a substance. In fact, the energy released by respiration is not used instantly but is stored in another molecule called ATP, until it is needed. More properly put, the energy is transferred from the glucose to ATP.

In general terms, more active people require more food. Males tend to need more energy foods than females, simply due to differences in body biochemistry. This is not an exact science, since different people do different activities and have different metabolic rates (the speed with which food is used up in the body). Rough estimates of the amount of energy used per hour in various activities are shown in the table. Actively growing teenagers require more energy than many adults, because rapid growth needs extra energy.

Activity kJ/hour Activity kJ/hour

sleeping 270 cycling 1500sitting 350 heavy manual labour 2000standing 430 playing football 2200slow walking 760 stair climbing 2300fast walking 1200 running 2500

The products of respiration are carbon dioxide and water. The carbon dioxide is excreted from the body via the lungs. The water tends to stay in the cell, or if it is not needed it is released into the tissue fl uid and, thence, the bloodstream. It is a fallacy to say that the water from respiration also leaves the body via the lungs. The lungs need to be kept moist in order for oxygen absorption to take place effectively.

The energy released by respiration is used for movement and to power the biochemical reactions that occur in the body.

Food, glorious food! 8Aa

8A

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8Aa


8Aa Advertising food

Pupil’s materials

Number and title Level Location Type Tasks

Advertising food Must/Should PB p7 Classwork Explaining 1

On a diet Must PB pp8–9 Classwork Explaining 2

8A Quick Quiz Must/Should ASP Classwork Starter 1

8A Quick Quiz Answer Sheet Must/Should ASP Classwork Starter 1

8Aa Quick Check Must/Should ASP Classwork Plenary 2

8Aa Word Sheet Must/Should ASP Classwork Plenary 4

8Aa(1) On a diet Must CHAP Access Explaining 2

8Aa(2) Testing for starch Must CHAP Practical Exploring 3

8Aa(3) Testing for fat Must CHAP Practical Exploring 3

8Aa(4) Testing foods 1 Must CHAP Practical Exploring 3, Exploring 4

8Aa(5) Testing for protein Should CHAP Practical Exploring 3

8Aa(6) Testing for sugars Could CHAP Practical Exploring 4

8Aa(7) Testing foods 2 Should/Could CHAP Practical Exploring 3, Exploring 4

8Aa(8) Food links Must CHAP Homework Starter 2

8Aa(9) Foods and tests Must CHAP Homework Homework 1

8Aa(10) Foods and adverts Should CHAP Homework Homework 2

8Aa(11) ELISA tests Could CHAP Homework Homework 3

SS44–45 Microscopes and slides Should Year 7 CHAP Skills Sheet Exploring 6

ObjectivesAll pupils must:

(1) recall that the word ‘diet’ has different meanings in science and everyday language

(2) recall what the major components of our diets are used for (energy, growth and repair, health)

(3) describe what a nutrition information label shows(4) perform tests for starch and fat. Correctly use the words carbohydrate, diet, fat, fi bre,

mineral, nutrition information, protein, raw material, starch, sugar, vitamin.

Most pupils should:(5) describe, perform and interpret results from tests for starch

and fat(6) perform and interpret results from tests for protein(7) explain how lack of fi bre can lead to constipation. Correctly use the word constipation.

Some pupils could:(8) describe the tests for water, protein, glucose and sucrose(9) explain what food allergies and intolerances are. Correctly use the words Biuret solution.

Topic notes• Targets for the topic can be accessed via the ActiveBook or

ActiveTeach from the link next to the initiator question.

Be prepared: 8AaStarter 3: food adverts cut from magazines and newspapers.Exploring 2: nutrition information panels from a variety of foods.

Exemplar topic plans

MUST

PB pages 8–9

Starter 1Starter 4Exploring 1Explaining 2Exploring 3Plenary 3Homework 1

SHOULD

PB pages 7–9

Starter 1Starter 4Explaining 1Exploring 2Explaining 2Exploring 3Plenary 4Homework 2

COULD

PB pages 7–9

Starter 1Explaining 1Exploring 2Explaining 2Exploring 3Exploring 4Plenary 1Homework 4

SHOULD 2 Yr KS3*

PB pages 7–12

8Aa Starter 18Aa Explaining 18Aa Explaining 28Aa Exploring 38Ab Explaining 18Ab Explaining 28Ab Explaining 38Ab Plenary 38Ab Plenary 48Ab Homework 3

*This table is repeated in 8Ab.

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8Aa

Topic task plannerUse these tasks to adapt the exemplar topic plans to your own needs. Many tasks can be adapted to become different types (e.g. ‘starter’ rather than ‘exploring’). AT or AB/AT at the top of a task means that the task depends on using the ActiveBook and/or ActiveTeach; where these symbols appear in brackets it indicates that the task can be carried out with or without their use.

Task Level NC Type Objectives Skills 1 KC 2 KP 3 RC 4 CO

Starter 1 M/S 4–7 Classwork whole unit PLTS (Rl) 3c

Starter 2 M 4 Classwork fi rst 2 topics PLTS (Rl) 3c

Starter 3 M/S/C 4 Classwork 5 PLTS (Tw) 2b 3a 3c, 3e a, c, i, j

Starter 4 M 4 Classwork 5 2b 3c, 3e c, e, j

Exploring 1 M 4 Classwork 1, 2 PLTS (Ct, Tw) 3c a

Exploring 2 M 4 Classwork 1, 2, 3 2a 3c a

Exploring 3 M/S 4–6 Practical 4, 6, 7 Num (T, B), PLTS (Ep, Tw, Ie) 1a, 1c, 2a, 3a 3c a, c, i

Exploring 4 C 7–8 Practical 7, 9 Num(T), PLTS (Ep, Tw) 1a, 1c, 2a, 3a 3c a, c, i

Exploring 5 S 6 Practical 8 1a 3c a, c, i

Exploring 6 S 6 Practical 8 PLTS (Ep, Tw, Ie) 1a 3c a

Explaining 1 M/S 5–7 Classwork 5 1a, 1b, 2b, 4a 1a 3c, 3e c, j

Explaining 2 M/S 4–6 Classwork 1, 2, 3, 4, 6, 7, 8 1a, 2a 3c a, c, i, k

Explaining 3 S 6 Classwork 8 3c

Explaining 4 S/C 6–8 Classwork 6, 7, 9 Lit (DS), PLTS (Rl) 1a 3c

Plenary 1 M/S 6 Classwork 2, 3, 8 PLTS (Ct) 3c

Plenary 2 M/S/C 4–6 Classwork 1, 2, 3, 4, 6, 7, 8 PLTS (Ct) 1a 3c

Plenary 3 M/S 4–6 Classwork 1, 2, 3, 4, 6, 8 Lit (WF) 1a 3c

Plenary 4 M/S 4–6 Classwork 1, 2, 3 Lit (WF), PLTS (Rl) 3c

Homework 1 M 4–5 Homework 1, 2, 3, 4 Num (C) 1a, 2a 3c

Homework 2 S 6 Homework 2, 3, 4, 5, 6, 8 Num (C) 1a, 2a, 3a 3c

Homework 3 C 7–8 Homework 10 Lit (EC) 2a 3c c, j

Homework 4 M 4 Homework 1 2a, 3a 3c c, j

Starters

1: Quick QuizAfl Use the 8A Quick Quiz for baseline assessment. Pupils can use

the 8A Quick Quiz Answer Sheet to record their answers.

2: Foods true and falseAfl Worksheet 8Aa(8) provides a true or false exercise that can be

used to determine how much pupils already know about nutrients and why they are needed (covering this topic and the next). You may wish to use only the fi rst question on this worksheet if you do not have much time for the starter activity. The phrases used on this worksheet will be met again if pupils are asked to construct the concept map in Topic 8Ae.

3: Food advertsGive pupils adverts for foods cut from newspapers and magazines. Ask pupils to imagine that they are working for an advertising agency looking to recruit people. The adverts are all from different people who have applied for a job. There is one job available. Pupils should work in groups to choose an advert that they think works the best at persuading people to buy that food. They should agree on two statements to explain their choice of advert. Each group appoints a spokesperson to report their group’s fi nding to the class – showing the class which advert they picked and giving the two reasons why the group thought it was the best (and giving the creator of that advert the job).

• Must: give pupils a limited choice of adverts.• Should: give pupils a larger choice.• Could: ask pupils to think about the language of adverts

themselves, identifying key phrases used in food advertising.

Resources (per group)Food adverts cut from magazines and newspapers.

4: Food and advertising ATThe AT video link on page 7 opens Food and advertising – in which Dr Jason Halford and Emma Boyland explain the effects of food advertising and how it is controlled. At the end of the video pupils should write down one sentence summarising what they have learnt from the video.

Exploring tasks

1: What do our bodies need food for?Ask pupils to work in groups to answer the question: What do our bodies need food for? Give them only a few minutes in which to come up with some suggestions. Ask the groups to read out their suggestions and use them as part of a discussion to agree on the three main things that food is used for: energy, growth and repair, and health. Having agreed on this, ask pupils to think up a mnemonic to remember these three things. A good suggestion might be: Enjoy Great Health.

2: Nutrition information labels (AT)Ask pupils to generate questions that they could answer from nutrition information labels (e.g. What are the main nutrients in food? Which sorts of foods contain mainly one sort of nutrient? Which sorts of food contain things that some people are allergic to?). Nutrition information labels cut from packets are handed out to groups of pupils who are then challenged to answer their questions and identify the main nutrients in foods in general. Ask pupils how information from nutrition labels can help them make healthier choices.

Advertising food 8Aa

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8Aa

Alternatively the third AT presentation link on page 8 opens Food labels – a presentation of four different nutrition information labels. Pupils should quickly discover that carbohydrates, proteins and fats are the main nutrients.

Resources (per group)Nutrition information labels cut from packets.

3: Practical: Simple food testsRemind pupils that many scientists are employed to check what is in foods to make sure that their labels are accurate and consumers can trust what they are buying. The scientists use the same sorts of tests for fat, protein and starch (a carbohydrate) that are given in the Pupil’s Book and on Worksheets 8Aa(2), 8Aa(3) and 8Aa(5).

The blue–black colour produced by the iodine test shows up better in powdered food samples that have been mixed with an equal volume of water. Other, non-powdered foods can easily be tested by adding ‘iodine solution’ directly to the food.

The test for fat is very simple, if a bit messy. A food sample is rubbed into a piece of paper. Filter paper tends to work best. A greasy mark, visible when the paper is held up to the light, indicates the presence of fat.

The Biuret test for protein involves using either pre-made ‘Biuret solution’ or sodium hydroxide and copper sulphate solutions. The Pupil’s Book indicates the former approach, since it is easier for pupils to do. Both approaches are indicated on Worksheet 8Aa(4). For both tests, the food sample has to be in water. A spatula of powdered food can simply be shaken with about 2 cm depth of water in the test tube. However, the tests work better if foods are mashed with 2–3 cm3 of water using a pestle and mortar fi rst. A positive result is indicated by a purple colour, which may take a couple of minutes to appear.

Before starting the practicals, show pupils the apparatus they will be using and ask them how they will use the apparatus in a safe way.

• Must: use worksheet 8Aa(4) to help them present their results. Do not do the protein test.

• Should: do tests for starch, fats and proteins and use Worksheet 8Aa(7).

Iodine solution stains skin and may irritate the eyes. Wear eye protection. Biuret solution and sodium hydroxide are irritants. Wear eye protection. Pupils should not eat the foods tested.

Resources (per group)Starch Test: Iodine solution (1 g iodine in 100 cm3 1.0 mol dm–3 potassium iodide solution); spotting tile; test tube(s); stopper(s); food sample(s); pipette, water; eye protection; Worksheet 8Aa(2).Fat Test: Food sample(s); fi lter paper; Worksheet 8Aa(3).Protein Test: Food sample(s); test tube(s); pestle and mortar; Biuret solution (obtainable from an educational supplier or made) or dilute sodium hydroxide solution (0.2 mol dm–3) (labelled irritant) and copper sulphate solution (0.1 mol dm–3); eye protection; Worksheet 8Aa(5).

4: Practical: More food testsFood standards scientists also test for sugars. Worksheet 8Aa(6) provides further food tests for two sugars (glucose and sucrose). This is a bit of a simplifi cation since other sugars will also be detected. The tests are not the same due to the different molecular structures of the sugars (glucose is termed a reducing sugar and sucrose is a non-reducing sugar). It is suggested that only the test for glucose is performed by pupils. The sucrose test is best done as a teacher demonstration. Note that glucose is not found in normal packet sugar (which is pure sucrose).

Boiling water hazard. Wear eye protection.

Resources (per group)Bunsen burner; heatproof mat; boiling tube; Benedict’s solution; tripod; gauze; pipette; food sample(s); pestle and mortar; eye protection; Worksheets 8Aa(6), 8Aa(7).Resources (for demonstration)Additionally for the sucrose test: dilute hydrochloric acid (0.5 mol dm–3) and sodium hydrogen carbonate solution (1 mol dm–3).

5: Practical: Testing for waterWater is an important component of the diet and some pupils may be interested in fi nding out which foods contain a lot of water. Food standards scientists also test the water content of foods, since some foods can have water pumped into them to make them look more appetising. Place anhydrous (blue) cobalt chloride paper on a food sample. It will turn pink in the presence of water. Obviously, food scientists use more complicated tests but this experiment provides another example of how components in food can be tested.

Cobalt chloride paper should be directly handled as little as possible. Hands should be washed if direct contact is made with the skin.

Resources (per group)Anhydrous cobalt chloride paper; forceps; food samples.

6: Practical: A fi bre providerPupils examine fi bre under a microscope. This is easily done with boiled celery or well soaked All-Bran®. Iodine stains the fi brous tissue (but point out to pupils that it does not change colour – we are not testing for starch). Pupils could be encouraged to work out what fi bre is made from, using their knowledge from Unit 7A about plant cell structure. Use Skills Sheets SS44 and SS45 from Year 7 CHAP.

Iodine solution stains the skin and may irritate the eyes.

Resources (per group)Microscope; boiled celery or 2-hour soaked All-Bran® in water; iodine solution (1 g iodine in 100 cm3 1.0 mol dm–3 potassium iodide solution); cavity slides; coverslips; eye protection; forceps; Year 7 CHAP Skills Sheets SS44 and SS45.

Explaining tasks

1: Pupil’s Book page 7 (AT/AB)Page 7 of the Pupil’s Book introduces pupils to food advertising and how it is controlled. Ask pupils what they think advertising is for. Ask them what food advertising they have seen and what impressions it has made on them.

• The AT video link opens Food and advertising (see Starter 4).

2: Pupil’s Book pages 8–9 (AB/AT)Pages 8–9 in the Pupil’s Book revise and extend work from KS2 on food substances and how the body uses them, before going on to introduce food tests. Worksheet 8Aa(1) is the Access Sheet.

• The AT video link on page 8 opens Food labels – in which Emma Boyland from the Kissileff Laboratory for the study of Human Digestive Behaviour, at the University of Liverpool, explains how food has changed over the years and how the labels have changed.

• The fi rst AT spreadsheet link on page 8 opens Nutrition information labels – in which pupils need to extract and interpret data from some food labels.

• The third AT presentation link on page 8 opens Food labels (see Exploring 2).

8Aa Advertising food

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8Aa

• The second AT spreadsheet link on page 8 opens Bread nutrition information – which contains the same data as on label B, allowing pupils to answer Question 2 electronically.

• The AT video link on page 9 opens Food tests – see Explaining 4.

3: Why do we need water?Tell pupils that people have been known to live for over 60 days without food but only for a few days without water. Explain that water is used as a solvent in the body (linking with ideas in Unit 8E), it is used to cool you down through sweating and is used to give cells their shape. It is also used as a raw material for some of the body’s reactions but it is not generally thought of as a nutrient. Remind pupils of work carried out in Units 7C and 7D on adaptations of animals. Explain that some animals, like oryx, don’t need to drink and obtain all the water they need from the plants that they eat. Explain that animals living in dry environments also have other ways in which to conserve precious water (e.g. camels produce very concentrated urine, only sweat when the temperature is above 41 °C and store water in their stomachs).

4: Food test videos (AB/AT)Afl The AT video link on page 9 opens Food tests – which shows

pupils a range of food tests. The fi rst AB document link on page 9opens Food test – which can be given to pupils before they watch the video. Ask them to complete the sheet to make predictions. You could challenge some pupils to explain their predictions. Allow pupils to watch the video presentation in which the various food tests are explained and demonstrated and then ask pupils to check their answers again. Ask them how useful they think it was to think about what they were going to watch before actually watching the video.

Plenaries

1: Thinking about diet (AT)Afl Use the following thinking skills questions as a plenary.

• CAP: not every individual chemical in a food is printed on its nutrition label. (Possible answers: if all the chemicals were included it would put people off buying the food; not everything in the food is known; some substances in the food are complicated mixtures and it makes more sense putting the name of the mixture on the label rather than all the chemicals in the mixture.)

• OOO: carbohydrates, proteins, fi bre, vitamins. (Possible answers: fi bre is not a nutrient; vitamins as we only need them in small amounts.)

• OOO: fi bre, water, sugar. (Possible answers: sugar is the only carbohydrate; sugar is the only nutrient; water is the only liquid; fi bre is the only one that won’t disappear when mixed with water.)

The second AT presentation link on page 9 opens Thinking about diet – a PowerPoint presentation version of this task.

2: Quick CheckAfl The 8Aa Quick Check sheet provides a set of answers to which

pupils need to construct the questions.

• Must: pupils write questions for answers 1–5.• Should: pupils write questions for answers 1–10. • Could: pupils write two questions for each answer 1–10.

3: I can… cloze exercise AB/ATAfl The second AB document link on page 9 opens a cloze

exercise summarising the content of pages 8–9. There is also an AT presentation version with answers.

4: Word defi nitionsAfl Give pupils copies of the Word Sheet for this topic but with

the defi nitions missing (either edit them out from the CD version of the sheet or photocopy with a piece of paper over the defi nitions). Ask pupils to put a number from 1–5 against each word to show how confi dent they are that they know the meaning (5 meaning ‘absolutely certain’, 1 meaning ‘no idea’). Then read out the words one by one and ask for a show of hands for CRI scores of 4 and 5 (see Introduction, page 17), identify the two or three words that pupils are least sure about and revise their meanings, before quickly running through the meanings of the other words.

Homework tasks

1: Worksheet 8Aa(9) provides simple questions on food and food tests.

2: Worksheet 8Aa(10) provides questions on food and advertising. 3: Worksheet 8Aa(11) is a comprehension type exercise on food

intolerance tests. 4: Ask pupils to keep a diary of everything that they eat before

the next science lesson (when they will examine their diaries in Starter 3).

Advertising food 8Aa

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Pupil’s materials


Keeping it balanced Must/Should PB pp10–11 Classwork Explaining 1

Poor diets Should PB p12 Classwork Explaining 2

Focus on: Diabetes and diet Could PB p13 Classwork Explaining 4

8Ab Quick Check Must/Should ASP Classwork Starter 1, Plenary 2

8Ab Word Sheet Must/Should ASP Classwork

8Ab(1) Keeping it balanced Must CHAP Access Explaining 1

8Ab(2) Poor diets Must CHAP Access Explaining 2

8Ab(3) Focus on: Diet and diabetes Should CHAP Access Explaining 4

8Ab(4) Newspaper article 1 – CHAP Classwork Exploring 3

8Ab(5) Newspaper article 2 – CHAP Classwork Exploring 3

8Ab(6) Food wheels – CHAP Classwork Exploring 4

8Ab(7) A Big Burger meal Should CHAP Homework Homework 1

8Ab(8) Balanced diets Should CHAP Homework Homework 2

8Ab(9) Food and activity Must CHAP Homework Homework 3

8Ab(10) Salt – good or bad? Should CHAP Homework Exploring 3

8Ab(11) The work of a food scientist Could CHAP Homework Homework 4

SS58 What food contains Must Year 7 CHAP Skills Sheet Exploring 1

8Ab Keeping it balanced

8Ab


(1) explain what a balanced diet is and why it is needed(2) recall at least one good source of each nutrient and why it is

needed(3) explain why more active people need more food (especially

carbohydrates)(4) recognise that advertising can have negative effects on people. Correctly use the words balanced diet.

Most pupils should:(5) recall that food contains stored chemical energy measured in

kilojoules(6) recognise that different cultures have all developed balanced

diets(7) describe some problems caused by not getting a balanced

diet(8) explain how eating too much fat can cause heart disease. Correctly use the words kilojoule, chemical energy, heart

disease, obese.Some pupils could:

(9) describe how diet can cause and control some diseases. Correctly use the words diabetes, insulin, kwashiorkor.


ActiveTeach from the link next to the initiator question.• Care should be taken when discussing ‘weight problems’ and

obesity since some pupils will be sensitive about their weight. You may help them by saying that being ‘fat’ used to be a sign of wealth and people strived to be fat. Our bodies are also very good at storing fat which was useful thousands of years ago when people were hunter gatherers but is not so helpful in ‘Western society’. Indeed, on a point of cultural understanding, there are many cultures (particularly African) that still put a higher status on people who are fat.

Exemplar topic plans

MUST

PB pages 10–11

Starter 1Exploring 1Explaining 1Exploring 5Plenary 3Homework 2

SHOULD

PB pages 10–12

Starter 1Exploring 1Explaining 1Exploring 2Explaining 2Explaining 3Plenary 1Homework 3

COULD

PB pages 10–12

Starter 3Explaining 1Exploring 4Explaining 2Explaining 3Plenary 5Homework 4

SHOULD 2 Yr KS3*

PB pages 7–12

8Aa Starter 18Aa Explaining 18Aa Explaining 28Aa Exploring 38Ab Explaining 18Ab Explaining 28Ab Explaining 38Ab Plenary 38Ab Plenary 48Ab Homework 3

*This table is repeated in 8Aa.

Be prepared: 8Ab Exploring 1: nutrition information panels.Exploring 3: food packaging, food advertisements, scientifi c magazine/newspaper reports about food.Explaining 3: a range of adverts for fatty/junk food.Explaining 5: a visit from a nutritionist.

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Topic task plannerUse these tasks to adapt the exemplar topic plans to your own needs. Many tasks can be adapted to become different types (e.g. ‘starter’ rather than ‘exploring’). AT or AB/AT at the top of a task means that the task depends on using the ActiveBook and/or ActiveTeach; where these symbols appear in brackets it indicates that the task can be carried out with or without their use.Also consider using one of the plenaries from the previous topic as a starter task in this topic.

Task Level NC Type Objectives Skills 1 KC 2 KP 3 RC 4 CO

Starter 1 M/S 5 Classwork 2 3c j

Starter 2 M 4 Classwork fi rst 2 topics PLTS (Rl) 3c

Starter 3 M/S 5 Classwork 1, 2 3c c, j

Starter 4 M/S 5–7 Classwork 2, 3, 4, 7 Lit (DS), PLTS (Tw, Ep) 3c a, j

Exploring 1 M/S/C 5–8 Classwork 2, 3, 5 Num (B), ICT (SS), PLTS (Ie) 2a, 3a 3c a, c

Exploring 2 M 4 Classwork 2, 3 ICT (WP), PLTS (Tw) 3a 3c j

Exploring 3 S 6–7 Classwork 1, 2, 3, 4, 5, 6, 7, 8 Lit (RR, DS), ICT (WP, PS) 3a 3c, 3e c

Exploring 4 M/S/C 4 Classwork 2 3c

Exploring 5 M/S/C 4–5 Practical 5 Num (M, C, B), PLTS (Ie) 1b 1a, 1b, 1c, 2a, 2b

3c a

Exploring 6 M/S/C 4–8 Classwork 1, 2, 5, 7, 8, 9 Lit (RR), ICT (IR), PLTS (Ie, Sm) 3c a, b

Explaining 1 M/S 6 Classwork 1, 2, 3, 4, 5, 7 3c j

Explaining 2 S 6 Classwork 6, 7, 8, 9 2b 3c, 3e d, j

Explaining 3 M/S 5–6 Classwork 4 2b 3c, 3e

Explaining 4 C 7–8 Classwork 9 3a 3c h, f

Explaining 5 M/S/C 4–8 Classwork 1, 2, 3, 4, 5, 6, 7, 8, 9 PLTS (Ep) 3c c, d, e, i, j

Plenary 1 M/S 5–6 Classwork 1, 2, 7 PLTS (Ct) 3c

Plenary 2 M/S 5 Classwork 2 PLTS (Rl) 3c j

Plenary 3 M/S 5–6 Classwork 1, 2, 3, 5 LIT (WF) 3c

Plenary 4 S 6 Classwork 7, 8, 9 LIT (WF) 3c

Plenary 5 M/S/C 4–8 Classwork 1, 2, 3, 4, 5, 6, 7, 8, 9 LIT (WF), PLTS (Ct) 3c

Homework 1 M 4 Homework 1, 2 3c

Homework 2 M 5 Homework 1, 2 3c

Homework 3 S 6 Homework 2, 3, 7, 8 3c d

Homework 4 C 8 Homework 5 Num (C) 3c

Homework 5 S 6 Homework 3, 6 LIT (RR, DS, EW), ICT (PS),PLTS (Ie, Sm)

3a 3c, 3e d

Keeping it balanced 8Ab

8Ab

Starters

1: Quick CheckAfl The Quick Check sheet provides a list of common foods, and

asks pupils to tick the main nutrients in each foodstuff. Pupils have 5 minutes to complete their sheets, then a class discussion can be held to compare opinions. If pupils are asked to complete the sheet in pencil, they can revisit it at the end of the topic and make any necessary corrections.

• Must: pupils simply draw in ticks to show the main nutrients in each food.

• Should: ask pupils to use two ticks for foods that contain a lot of a nutrient, and one tick for foods that only contain a little of it.

2: Foods true or falseAfl Starter 2 from the last topic can be used here if not already

used.

3: What’s a good diet?Ask pupils to look at their diet diaries if they were asked to do them in Homework 4 in the last topic. Ask them to look at the foods that they have eaten and say whether they think they have a healthy diet or not, and if not what could be done to improve their diets.

You can also use the information collected by pupils to discuss whether how they recorded what they ate was appropriate to the task and any conclusions made. Most pupils will not have noted down the exact amounts of food, and this makes it diffi cult to do a detailed, accurate analysis of diets.

4: ObesityObesity (being very overweight) has trebled in the last 30 years and now about 15% of children in the UK are obese. Share these facts with pupils and ask them to discuss in groups: a) why they think this has happened; and b) what can be done about it. After 10 minutes ask a spokesperson from each group to summarise the thoughts of the group.

Exploring tasks

1: What’s in our food? (AB/AT)Ask pupils to look through nutrition information panels to fi nd the answers to questions such as: ‘Which food contains the highest amount of fat?’ Pupils should be encouraged to frame their own questions.

Alternatively, the nutrition information on Skills Sheet 58 from Year 7 CHAP could be used. Or the AB spreadsheet link on page 10 opens What food contains – a spreadsheet containing this information.

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Bar charts could be plotted to show the levels of nutrients in different foods, or the foods rich in certain nutrients. The charts could be compared with any Venn diagrams prepared in the previous topic. They could be asked about the accuracy of their own experiments in relation to this, introducing the fact that food scientists use much more sensitive methods to determine the amounts of food substances in a food (to make sure that foods contain what they say they contain).

• Could: pupils use the spreadsheet alongside information panels taken from foods and current prices to answer questions such as: ‘Are high-protein foods more expensive than others?’; ‘What are good sources of protein in a vegetarian diet?’; ‘How does the nutrient content of pre-packaged meals compare with freshly cooked meals?’

Resources (per group)Nutrition information labels; Year 7 CHAP Skills Sheet 58. Optional: sheet of current food prices downloaded from the internet.

2: Food substance summaryAsk pupils to work in groups to write a summary page on one of thefood substances. They should include a food that contains a good source of the food substance and the role played by the food substance in the body. The pages could be brought together to makea booklet designed to be left out in, for example, a doctor’s surgery.

3: Media questionsGive groups of pupils access to food packaging, advertisements, scientifi c media reports and newspaper reports, using them to raise a series of questions.

Worksheets 8Ab(4) and 8Ab(5) could provide the focus for a class discussion on how science is reported in newspapers, or they can be used directly as secondary sources of information. Worksheet 8Ab(10) provides a way of covering some of these ideas if less time is available (or as a homework task).

One question could then be used as the basis of a small media-based research project. Before starting, pupils should be made aware that claims and theories are often biased depending on where they have come from. Suggested questions: ‘Are breakfast cereals good for you?’; ‘Are foods that have less fat always preferable?’; ‘Can eating too much salt harm you?’; ‘What diets do athletes follow when they are in training?’; ‘What foods would you advise someone to eat to reduce the chance of heart disease?’; ‘What should pregnant women make sure they eat enough of?’

Pupils should be asked about how confi dent they are of what they have discovered. They should also come to appreciate that scientifi c knowledge is not always complete, and interpreting the results of investigations using humans is often diffi cult.

Pupils could be asked to design a poster, a leafl et for a doctor’s surgery or organise a class debate about their researched question(s).

Resources (per group)Food packaging; food advertisements; scientifi c magazine/newspaper reports about food; Worksheets 8Ab(4), 8Ab(5), 8Ab(10).

4: Food wheelsUsing Worksheet 8Ab(6), pupils could construct a ‘food wheel’. There are many possibilities on how to fi ll this in. Some suggestions are listed below.

• Must: nutrient types on the outer ring of wheel 2 and a good source of each on the inner one.

• Should: nutrient types on the outer ring of wheel 2 and what they are used for on the inner one.

• Could: ask pupils to research E numbers and put the E numbers on the outer ring and their names on the inner ring. Pupils could be challenged to think up their own ideas on what to put on the wheels and to make more than one wheel.

Pupils are asked to make holes in their wheels using scissors and Plasticine®. Some teachers may wish to do this themselves.

Resources (per pupil)Worksheet 8Ab(6); scissors; brass ‘butterfl y’ paper fastener; Plasticine® lump.

5: Practical: Energy in foodExploring 1 (Energy in food) from Topic 7Id is also suitable for use here. Various foods are burnt to compare energy contents.

6: Research workAsk pupils to use books and/or the internet to fi nd out about diet and dietary problems. Ask pupils to produce a list of key points as their report.

• Must: pupils research the nutrients needed by another named mammal and the range of foods it eats.

• Should: pupils research defi ciency diseases (e.g. rickets); or the problems of a vegan diet; or the work of a food scientist.

• Could: pupils research diseases that require special diets (e.g. coeliac disease, phenylketonuria).

ResourcesLibrary/internet access.

Explaining tasks

1: Pupil’s Book pages 10–11 (AT/AB)Worksheet 8Ab(1) is the Access Sheet.

• The AT video link on page 10 opens Changing diets – in which Dr Jason Halford from the Kissileff Laboratory for the study of Human Digestive Behaviour, at the University of Liverpool, talks about the current recommendations for a healthy diet.

• The second AT presentation link on page 10 opens The food pyramid 1 – where pupils take it in turns to drag food items into the correct places on a food pyramid.

• The AB document link on page 10 opens The food pyramid 2 – in which pupils use food icons to create their own food pyramid using a word processing program.

• The AB spreadsheet link on page 10 opens What food contains (see Exploring 1).

• The AT video link on page 11 opens Recommended amounts – in which Emma Boyland talks about GDAs.

• The AB spreadsheet link on page 11 opens What’s in it? – a spreadsheet containing the same data as table C, with questions to answer using that data. Questions 4, 5 and 7 could also be answered using this spreadsheet.

2: Pupil’s Book page 12 (AT/AB)Worksheet 8Ab(2) is the Access Sheet.

• The fi rst AB document link opens Balanced diet – in which pupils examine the food eaten by someone during the course of a day and write a short report on how balanced the diet was for that day.

• The second AT video link opens Food and fashion – in which Dr Jason Halford explains how advertising and fashion could cause eating problems in some people.

8Ab Keeping it balanced

8Ab

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3: What effect do images have?Show pupils a range of adverts that encourage us to eat fatty/junk foods or make us feel overweight (e.g. many fashion shoots). Show pupils the adverts in turn (it’s a good idea to scan them if you can and display on an interactive whiteboard). Ask pupils what the advert or image makes them feel like. Point out that the adverts for the fatty foods all feature healthier-than-normal looking people who are undoubtedly thin and very active. Photos from fashion shoots often feature very thin people who are very good looking – helping to form the link in some people’s minds that in order to be attractive you have to be very thin. If you can, show pupils photos that have been obviously Photoshopped to make people look younger/more attractive. This is reasonably easy to do with adverts for fi lms featuring older movie stars (e.g. Robert Redford on the poster for the fi lm Lions for Lambs). Encourage pupils to make the connection that what they see in the media is not necessarily real life.

Resources (per group)Range of adverts for fatty/junk foods.

4: Pupil’s Book page 13 (AT/AB)Worksheet 8Ab(3) is the Access Sheet.

• The AT video link opens Diabetes – in which Dr Jason Halford explains some current thinking on why more people are developing type II diabetes.

• The AB spreadsheet link opens Diabetes rates – a spreadsheet in which pupils construct a line graph to show the trends in the number of people diagnosed with diabetes in the last 50 years, together with some questions.

5: Visit from a nutritionistInvite a nutritionist to talk to the class about balanced diets. They should be asked to talk not only about diets but also about their career and what they do. Encourage pupils to do some background research and to think of some questions to ask before the visit.

Plenaries

1: Thinking about balanced diets (AT)Afl Use the following thinking skills questions as a plenary.

• PMI: school meals should always provide a balanced diet. (Possible answers: P – pupils would stay healthy; M – it might restrict the choice of food; I – is it possible to do this and still keep the meals interesting?)

• PMI: there are too many different foods to choose from when you go shopping. (Possible answers: P – it’s always good to have lots of choice; M – you may not choose the right ones for a balanced diet, it takes longer to shop; I – would it help to make a list fi rst?)

• CAP: not everyone eats enough vegetables. (Possible answers: some people can’t eat vegetables for medical reasons; children are often fussy eaters; not everyone knows that vegetables are good for you, vegetables are not available in some very poor regions or regions hit by natural disasters.)

• CAP: it is hard for some people to buy the foods that they need. (Possible answers: some people don’t live near large supermarkets; some people can’t afford to buy much food; healthy foods are more expensive than ‘junk’ food.)

• OOO: vitamins, starch, sugars, fats. (Possible answers: vitamins do not provide energy and are only needed in small amounts; fats are the only ones used for insulation.)

• OOO: meat, fi sh, vegetables, nuts, dairy products. (Possible answers: vegetables are the only things that contain fi bre and lots of vitamins and minerals, or the things that do not contain much fat.)

The fi rst AT presentation link on page 12 opens Thinking about balanced diets – a PowerPoint presentation version of this task.

2: Quick CheckAfl The Quick Check sheet provides a list of common foods, and

asks pupils to tick the main nutrients in each foodstuff and may have been used in Starter 1. Revisit Starter 1, asking pupils to correct their answers. Extend the task by asking pupils to colour in red the foods that are important for energy, green for foods that are important for health and blue for foods that are important for growth and repair.

ResourcesColoured pencils; Quick Check sheet 8Ab.

3: I can… cloze exercise AB/ATAfl The AB document link on page 11 opens a summary cloze

exercise covering the material on pages 10–11. There is also an AT presentation version with answers.

4: I can… cloze exercise AB/ATAfl The second AB document link on page 12 opens a cloze

exercise covering the material on page 12. There is also an AT presentation version with answers.

5: Quiz designAsk pupils to design a quiz sheet about this topic (and the last) and swap their sheets with other pupils for them to answer. These could be done in the same format as the Quick Quiz (i.e. multiple choice), which will make any marking of correct/incorrect answers easier.

Homework tasks

1: Worksheet 8Ab(7) contains simple questions about balanced diets.

2: Worksheet 8Ab(8) contains questions about balanced diets. 3: Worksheet 8Ab(9) asks pupils to compare the diets of two

people, with questions on problems caused by poor diet. 4: Worksheet 8Ab(11) demands a lot of calculation work (to work

out the energy content of some foods). 5: Page 12 of the Pupil’s Book mentions different diets in different

cultures. Ask pupils to research a short presentation/report on what their families eat. Pupils should also ask adults with which they have contact about what they used to eat. They could compare this to their own diets and describe the main ways in which diets have changed over the years, commenting on whether this change is good, bad or a combination of both. Finished presentations/reports should also describe what balanced diets are and how people can ensure that they have balanced diets.

Keeping it balanced 8Ab

8Ab

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Pupil’s materials


You’ve got guts Must/Should PB pp14–15 Classwork Explaining 1

8Ac Quick Check Must/Should ASP Classwork Plenary 2

8Ac Word Sheet Must/Should ASP Classwork Homework 4

8Ac(1) You’ve got guts Must CHAP Access Explaining 1

8Ac(2) A model small intestine 1 Must CHAP Practical Exploring 2

8Ac(3) Guts! Must CHAP Classwork Exploring 1, Plenary 4

8Ac(4) Digestive system parts Must CHAP Classwork Exploring 1

8Ac(5) In the gut 1 Must CHAP Homework Homework 1

8Ac(6) In the gut 2 Should CHAP Homework Homework 2

8Ac(7) The glycaemic index Could CHAP Homework Homework 3

8Ac You’ve got guts

8Ac


(1) recall that digestion is the breaking down of food (2) recall the positions, names and functions of the organs in the

digestive system(3) recall that teeth grind up the food. Correctly use the words anus, digestion, gullet, gut, large

intestine, rectum, small intestine, stomach. Most pupils should:

(4) describe the role of enzymes in digestion (5) describe what happens during ingestion, absorption and

egestion(6) explain how food is moved through the gut by muscular

contractions(7) describe a benefi t of bacteria in the gut. Correctly use the words absorption, contract, egestion,

elimination, enzyme, faeces, ingestion, insoluble, molecule, saliva, soluble.

Some pupils could:(8) recall that the muscular contractions of the gut are called

peristalsis(9) recall that the salivary gland releases saliva (10) explain why sugars from some carbohydrates take longer to

get into the blood than others. Correctly use the words peristalsis, salivary gland.


ActiveTeach from the link next to the initiator question. • Pupils will have met the idea of particles in Unit 7G What a waste!

but some may need help with the concept of a molecule, unless Unit 8F Materials and recycling has already been covered. At this stage it is suffi cient to say that food substances are made up of particles called molecules.

• The gullet is more properly called the oesophagus (a word not found in the pupils’ materials).

• The enzyme in saliva is called amylase and it chops up starch into a sugar (called maltose). The Pupil’s Book and worksheets simplify this slightly to imply

8A Food, glorious food!...(L7) Describe how nutrients are supplied to cells via the blood and tissue...

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