SCIENTIFIC

METHOD- PART 2

Scientific Method• Series of steps that help solve a problem

• not always the same series of steps for each scientist, but still

follows the same principles

• Goal is to solve a problem or to better understand an

observed event

• Helps determine fact from opinion

Common Steps of the Scientific Method

1. Define the Problem

2. Research

3. Form a Hypothesis

4. Collect Data• Also known as testing the hypothesis

5. Analyze Data

6. Form Conclusions

7. Communicate Discoveries and Evaluate Results

1. Define the Problem

• Usually in the form of a question

• Come from observations (information obtained

through your senses), descriptions, and

categorizations

• Ex – Why don’t the lights come on when I flip the light

switch?

2. Research/Gather Information

• Helps give you some background knowledge of the

problem

• Eliminate as many reasons for the problem as you can with

common sense, observations, and using previous knowledge.

• Collect data from libraries, books, Internet, magazines,

etc.

3. Form a Hypothesis

• A proposed answer (educated guess) to the problem

based on what is already known

• Typically in an if/then format

• Must be specific and testable

• Can be revised by additional observation or

experimentation

4. Collect Data/Test Hypothesis

• Hypotheses can be tested many ways:

1. Making Observations,

2. Building a Model, or

3. Performing an Experiment

• Measurements, observations, descriptions,

and categorizations expressed in tables,

graphs, etc.

• 2 types of data:

1. Quantitative Data

2. Qualitative Data

Quantitative Data

• Descriptions (in words) of phenomenon• Color, odor, texture, taste,

etc.

• Usually comes from observations

• Useful to report what happens, but not how it happens

• Objective (the same no

matter who measures

them) numeric

measurements

• Counts, time, mass,

volume, temperature,

etc.

Qualitative Data

Controlled Experiment

• ONLY 1 factor is tested• all other factors must be constant

• Usually always have a control – group that receives no treatment; occurs under normal circumstances• gives a standard to compare results obtained from experimental

group

• Experimental group – group that has 1 variable purposefully changed

Variables• Independent variable – factor that is being changed

or manipulated by the experimenter

• found on x-axis of a graph

• Dependent variable – Observed and measured data in an experiment; results of an experiment

• found on y-axis of a graph

• Constants/controlled variables - Conditions that are kept the same whether it is in experimental or control group

• allows scientist to be more confident that the results of experiment were due to a change in the independent variable

5. Analyze Data

• Record data in tables and charts

• Review data and look for trends or patterns in the

data.

6. Form Conclusions

• Decide whether the data supports or rejects the

hypothesis

• Supports hypothesis - repeat experiment

• allows for more certainty in results when an

experiment is repeated and the results remain the

same

• When data supports the hypothesis, determine

whether the results are by chance (non-significant)

or not by chance (statistically significant)

• Rejects hypothesis – revise hypothesis and test

again

7. Communicate Discoveries and Evaluate

Results

• Scientists publish their work in scientific journals such

as Scientific American, Discover, and Science

• Allows for peer review

• helps cut out bias (occurs when what the scientist expects

changes how the results are viewed) in research

Scientific Theory• A set of related hypotheses, observations, and

experimental results that have been tested and supported many times by many scientists

• Never proven; only supported

• Always subject to change based on new evidence

• Ex: natural selection, cell theory, germ theory of disease

Check for Understanding

• Write a hypothesis for the following experiment: The

affect of sunlight on plant growth

• List three key characteristics of a good experiment.

An experiment was conducted to test how UV light affected

frog egg production. Five treatment groups were used.

The first group received no UV light, the second group

received 1hour of UV light a day, the third group received 2

hours of UV light a day, the fourth received 4 hours of UV

light a day and the fifth received 8 hours of UV light a day.

Each treatment group had the same species of frogs, same

number of frogs, same food and water, and same

temperature.

• IV ______________________________

• DV _____________________________

• CG ______________________________

• CV_____________________________

• If you made a graph from the above experiment, what

would go on the x axis? Y-axis?

Data Tables and

Graphing- PART 3

Data Tables• Independent variables should be listed in the

first column (on the left).

• Dependent variables should be listed in a

column to the right of the independent

variable.

Elodea Bubble Production

Distance from Light

(cm)

O2 Bubble Production Rate

(bubbles/min)

10 40

20 20

30 10

40 5

50 2

Essential Elements to a Graph

• DRY MIX

• Dependent, resultant

on Y

• Manipulated,

Independent on X

• Scaled

• Title that is Y vs. X

• Units included in title

and axes labels

Graphing Relationships

Direct Variation (proportion) -

What one variable does, the other

also does!

•Gives a straight line graph

Inverse Variation (proportion) -

What one variable does, the other

does the opposite!

•Gives a curved line graph

Force vs Acceleration

0

5

10

15

20

25

30

0 2 4 6 8 10 12 14 16

Force (N)

Acce

lera

tio

n (

m/s

/s).

....

..

Wavelength vs. Frequency

0

2

4

6

8

10

12

14

16

18

20

0 100 200 300 400 500 600

Wavelength (m)

Fre

qu

en

cy (

1/s

)...

..

Types of Graphs

1. Bar• Used to show information collected by counting

• One time only measurements

2. Circle• Used to show how a total amount is divided into

parts

• Used to compare percentages or parts of a whole

3. Line• Show a change over time

• Can use more than one line on a graph

Graphing

DATA COLLECTION AND

MEASUREMENTS- PART 4

Measurements• When scientists collect data from an experiment, they

may take measurements

• SI (The International System of Units) is the system of

measurement used by scientists

• based on multiplies of 10

• easy to convert from one unit to another

The 5 Major Base Units in SI System

1.) Length: meter

2.) Volume: liter

3.) Mass: gram

4.)Time: second

5.) Temperature: Kelvin

(we’ll use Celsius

scale)

**We will be working the most with #1-3**

**KNOW THEM ALL**

Common Metric Prefixes• Used to select a measurement that makes the

most sense for what is being measured

King Kilo 1000

Henry Hecto 100

Died Deca 10

By base 1

Drinking deci 0.1

Chocolate centi 0.01

Milk milli 0.001

Conversions

Kilo down to right

Hecto

Deca

base

deci

centi

milli Up to left

Sample Problems

1. 100 cm = _________m

2. 7500 km = ________cm

3. 1500 mL = ________L

Sample Problems

1. 789.45 m = _________mm

2. 0.345 cm = _________m

3. 98.68 mL = _________L

Precision and Accuracy

• Precision – measure of the degree to which

measurements made in the same way agree

with each other; how close measurements

are to each other

• Accuracy – the degree to which the

experimental value agrees with the true or

accepted value; how close measurements

are to the accepted value

Scientific Measuring Instruments

• The more decimals in the recorded measurement, the

greater the precision.

• An instrument that is marked is read to the next place, which

must be estimated.

• A 10 mL graduated cylinder is more precise than a 100 mL

graduated cylinder.

Example

• Lets say you know that you weigh 125 lb. You weigh

yourself on a scale three times and these are the

results:

• Weight 1: 120 lb

• Weight 2: 115 lb

• Weight 3: 105 lb

* What can you say about the instrument?

Example• You go to a friend’s house and use their

scale (you know you weigh 125 lb) and you

weigh yourself 3 times and you get this

reading:

• Weight 1- 115 lb

• Weight 2- 115 lb

• Weight 3- 115 lb

* What can you say about this scale?

Reading Instruments Practice

78.51 g

*in order to be precise the last digit has to be guessed

Reading Instruments Practice

32.1 mL

Technological

Design- PART 5

Technology vs. Science• Science and technology are NOT the same

• Science – the study of the natural world to understand how it functions

• Technology – the application of science to help people• Technology changes the natural world to meet human needs or

solve problems

Investigations• Scientific investigation - determine the

relationship between an independent and

dependent variable described by a hypothesis

• the results of scientific investigations can advance

science knowledge.

• Technological investigation - design products or

processes to meet specified needs

• the results of technological designs can advance

standard of living in societies.

Technological Design

• There are four stages of technological design:

1. Problem identification

2. Solution design (a process or a product)

3. Implementation

4. Evaluation

Keys to GOOD Technological Design

1. Cost effectiveness (lowest cost for production)

2. Time effectiveness (least amount of time for

production)

3. Materials used are: available, durable, and not

harmful to users

• There are tradeoffs among the various criteria

• Ex: the best material for a specific purpose may be too

expensive

*Benefits need to exceed the risk*

Scientific Investigation Technological Design

Identifies a problem – asks a

question

Identifies a problem or need

Researches related information Researches related information

Designs an investigation or

experiment

Designs a process or a product

Conducts the investigation or

experiment – repeated trials

Implements the design or the

process – repeated testing

Analyzes the results Analyzes the results

Evaluates the conclusion – did

the results refute or verify the

hypothesis

Evaluates the process or product

– did it meet the criteria

Communicates the findings Communicates the product or

process

Check for Understanding• What is the main purpose of technology?

• How does the scientific method differ from technological

design?

• What are the three steps that are the same in both of

the processes?

• In which part if the technological design process would

you modify and refine a product?

Swing

Force (N)

Wood

Distance (ft)

Aluminum

Distance (ft)

Alloy

Distance (ft)

100 10 15 25

200 20 22 30

300 25 35 80

400 100 140 140

500 200 225 200

600 300 400 300

A baseball bat company is testing a new mixture of metals (alloy) that they claim will improve the power of its bats for very powerful batters. Given the provided data of three bat compositions, swing force, and resulting ball travel distance, what conclusion can be made regarding this new composition? A. The alloy is more cost efficient.B. The alloy is a better material than aluminum or wood.C. The alloy is better for less powerful batters only.D. The alloy is better for more powerful batters only.

You're working with a group of classmates to design a

mousetrap car. Which step should be completed last?

A. Testing the car

B. Designing the car

C. Modifying the design

D. Researching simple machines

MICROSCOPES-

PART 6

Microscopes

•Provides an enlarged image of an

object

•2 basic types:1. Light microscope

2. Electron microscope

Light Microscopes•Type of microscope found in most schools

•Uses natural light or a light source to magnify structures

•Allows scientists to view living and preserved specimens

•2 main types:1. Simple light microscope – only one lens

2. Compound light microscope – 2 or more lenses

Electron Microscope• Uses a beam of electrons to magnify specimens

• Scientists cannot use to view living specimens because they are in a vacuum

• Has a greater magnification that light microscopes

• 2 basic types:

1. Scanning electron microscope (SEM)

2. Transmission electron microscope (TEM)

Scanning Electron

Microscope• Electrons pass over the object giving a scan

of the surface of the object

• Gives a 3-D image

Transmission Electron

Microscope• Electrons pass through the

object

• Only 2-D image

• Very detailed view of

internal structure

Magnification

• How large the image appears compared to its

normal size

• Ex – 200x means that the object appears 200 times

larger than it’s actual size

• Calculated by multiplying the ocular lens

power by the power of the objective

10 x 40 = 400X

Resolution• A measure of the clarity of an image

• Poor resolution = blurry/fuzzy appearance

Preparing a Wet Mount

Slide1. Place specimen to be viewed in center of slide

2. Use a dropper to place one drop of water

directly on the specimen

3. Place the coverslip at a 45 degree angle with

one edge touching the water drop, and gently

let the other side go to so that is falls directly

over the specimen

Drawing Specimens1. Use a pencil – this allows for corrections to

be made

2. Draw what you see to scale. The circle represents the viewing field as seen through the eyepiece.

• If the specimen takes up the entire viewing field, make sure the drawing reflects that.

3. All drawing should have clear labels written on the outside of the circle, including the specimen name and total magnification

Body Tube

Nosepiece

Objectives

Stage Clips

Light

Ocular lens

(Eyepiece)

Arm

Stage

Coarse Adjustment

Fine Adjustment

Base

Diaphragm

General Procedures for Using

the Light Microscope

• Always carry the microscope with 2 hands (one

on the arm and the other on the base)

• Always store the microscope with the cord

wrapped around the base of the scope, the

scanning power clicked into place, and the cover

over it

• NEVER force an objective into place or force the

knobs to make the stage hit the objectives

• ONLY use lens paper for cleaning

• Do not remove the microscope slide unless the

scanning power objective is clicked into place

Focusing on a Specimen1. Always start with the scanning objective in

place

2. Use the coarse adjustment knob to bring

the stage all the way up

3. Rotate the coarse adjustment knob so that

the stage starts to move downward and the

object comes into focus

• If you don’t focus on the object using this

power, you will not be able to see it at the

higher powers!

4. Switch to low power once you’ve focused

on the object with the scanning power and

refocus on the image using the coarse

adjustment knob.

• Again, if you haven’t focused on the object with

this objective, you will not be able to see the

object using the next objective

5. Switch to the high power objective and

ONLY use the fine adjustment knob to

focus on the object.

• If you have a microscope slide without a

coverslip or a thick slide, you will not be able to

use this objective or you will break it!

TroubleshootingOccasionally you may have trouble with working your microscope. Here are some common problems and solutions.

1. Image is too dark!Adjust the diaphragm, make sure your light is on.

2. There's a spot in my viewing field, even when I move the slide the spot stays in the same place!Your lens is dirty. Use lens paper, and only lens paper to carefully clean the objective and ocular lens. The ocular lens can be removed to clean the inside. The spot is probably a spec of dust.

3. I can't see anything under high power!Remember the steps, if you can't focus under scanning and then low power, you won't be able to focus anything under high power. Start at scanning and walk through the steps again.

4. Only half of my viewing field is lit, it looks like there's a half-moon in there!You probably don't have your objective fully clicked into place..

Studying Life

Learning Objectives

List the characteristics of living things.

Identify the central themes of biology.

Explain how life can be studied at different levels.

Biology

Biology is the study of life.

But what IS life?

Characteristics of Life

Genetic code

Grow and

develop

Respond to their

environment

Reproduce

Homeostasis

Metabolism

Evolve

Made of cells

Big Ideas in Biology

1. Cellular Basis of Life

2. Information and Heredity

3. Matter and Energy

4. Growth, Development, and

Reproduction

5. Homeostasis

6. Evolution

7. Structure and Function

8. Unity and Diversity of Life

9. Interdependence in Nature

10. Science as a Way of Knowing

Fields of BiologyGlobal EcologyBiotechnologyPaleontologyEntomologyMolecular Biology