The Experiment

You are going to conduct an experiment of your choice. It must be a quantitative experiment, meaning you will collect numerical data, e.g. height, time taken to fall, height of ramp or how far travelled and statistical results that can be compared, e.g. how high or how long?

You can choose one of the experiments from the list of ideas and decide how to design it and set it out or you can choose to use one of your own ideas.

• The Gravitational Pull - using an item of your choice, measure how long it takes for an item to fall from different heights.OR use different weighted objects and see how log it take each item to fall from the same height.

• The Ice Cream Test - Place a set amount of ice cream in a sieve or funnel over a measuring jug - measure how much ice cream has melted at different time intervals.

• The Mentos Trick - Place a different number of Mentos into bottles of diet coke. Measure the heights of the reaction depending on the number of Mentos.

• Elasticity - Add different weights to something elastic. Measure the distance that the elastic flexes (stretches) depending on the weight.

• Growing Mould - Using a small amount of water begin to grow mould on a piece of bread. (To speed up the process place it in a sealable bag, in the dark). Monitor the size of the mould over a series of days and weeks.

• Rebound Test - Measure the rebound height of a ball when dropped form different heights.

• Sugar Test - Dissolve a set amount of sugar in a cup. Change the temperature of the water and see how long it takes the sugar to dissolve. Take care not to burn yourself.

• Speed Challenge - Using a remote control vehicle measure the time it takes for the vehicle to travel different distances.

• Ramp Challenge - Using a toy vehicle and a ramp, change the angle of the ramp and measure the time taken for the toy to travel down it.

• Chocolate Test - Using a set amount of chocolate, measure how long it takes the chocolate to melt at different temperatures. Never leave the chocolate melting while you are somewhere else.

• The Pendulum Test - Measure the time taken for the pendulum to completely stop when it is raised to different heights.

Experiment Ideas

A Successful Experiment

It is important for an experiment to be a fair test.

• This means everything should stay the same (including; equipment, location of experiment, amounts of different equipment you will use), except for the independent variable which you will change to get different results. E.g. number of Mentos, height of ramp, temperature of water.

• The experiment must be repeatable lots of times – allowing you to change one variable and get new results for each test.

• As you conduct your experiment, record your results in a table, which you can later plot on a graph.

Step One: Design - Ask

Your first step is to decide what you want your experiment to achieve.- What is the goal? - What are you trying to figure out?

• I am investigating... (E.g. if the height from which an object is dropped affects theamount of time it takes to reach the ground).

What do you think will happen and what result(s) do you expect?Do you have an idea of what might happen? This is called a hypothesis.

• My hypothesis is... I think this because... (E.g. My hypothesis is the higher an object is dropped from, the longer it will take to reach the ground. I think this is because it has a further distance to travel).

Step One: Design - Build

Your next step is to decide how you are going to conduct your investigation.

What equipment will you use and how should it be set up?

However, there are a few things to consider first.

Step One: Design - Build

Your dependent variable is the thing that you are investigating, that will give you your results (it should just be one thing). You do not have control over this, and it will change due to the independent variable.

• What is your dependent variable? E.g. the time it takes the car to travel so many metres. (The time is dependent on the distance the car travels).

Step One: Design - Build

Your independent variable is the part of your experiment that you will change. You control this.It should be a change in amount or a number of something, e.g. height, weight or angle, so remember to think about the units it is measured in.

• What is your independent variable? E.g. the distancethe car travels 1m, 5m, 10m, etc.

Step One: Design - Build

Your control variables are the things you are going to keep the same throughout the whole experiment to make sure it is a fair test. If they change at all they could impact your results.• What are your control variables? E.g. the same car,

the same surface, the same direction and speedsetting, same way to measure time, etc.

Step One: Design - Build

Now it’s time to think about your equipment and what items you will use. Remember to make sure that your equipment is safe and won’t harm anybody. Only use ovens/microwaves, with adult supervision, or consider other ways to change temperature. (E.g. do the experiment in different rooms or different locations).

• How will you set up your experiment?Use the space below to draw or upload a sketch of how it will be set up. Be sure to label the items that you have drawn.

Step Two: Test

Have a few trial runs of your experiment to check that your equipment works. Try altering your independent variable and make a note of how the dependent variable changes. E.g. move the chocolate from table to window or shade to sunny location.

• Did your experiment work?

• Did your trial results match your hypothesis? If not, whydo you think this is?

Step Two: Improve

Following your test runs, think about any changes you need to make.These changes could be for many reasons; do you need to make your experiment safer, more convenient, easier to use or more accurate?

• What changes will you make to your experiment?

Step Two: Improve

After you have made changes, follow the engineering design cycle again to be sure that the changes are appropriate and will work.

You may need to make more changes, and go round the cycle a third, fourth or even fifth time!

Step Three: Results

Before you write your results down, it’s important to remind yourself of what you will be doing.

• What is your independent variable? What unit will you beusing to measure it?

• What is your dependent variable? What unit will you beusing to measure it?

• What are your control variables?

Independent Variable: Unit:

Dependent Variable:Unit:

Step Three: Results

Step Three: Results

Many scientists and engineers use graphs to display their results. This helps them to identify trends and draw conclusions from their work.

Use the empty graph on the next pageto plot a scatter graph.

Along the x-axis (horizontal) you will have your independent variable, and along the y-axis(vertical) you will have yourdependent variable.

X - (Independent Variable) Enter title and units in the text box

Y -

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Results

Step Three: Results

Anomalies are points that don’t match up with the trend or pattern - they are the odd ones out. They are sometimes because of an incorrect test or a mistake with the data.

Print out your graph and circle any anomalies, take a picture and uploaded here…

• Now that you have plotted your graph, can you seeor identify any patterns?

• Are there any anomalies on your graph?

Step Three: Results

• Do your results follow a line, or a curve?Scientists and engineers often use a line of best fit to demonstrate any trends. This is a straight line which has the same number of points above and below the line (excluding anomalies). The line of best fit doesn’t necessarily go through any of the crosses, but sometimes it can do. It usually doesn’t go through zero.

• Draw a line of best fit on your graph if it is appropriate.

Step Three: Results

Does your graph show a positive or negative correlation?

A positive correlation is shown when one variable increases, the other also increases.

A negative correlation is show as one variable decreases the other also decreases.

Step Three: Results

Now that you have drawn a line on your graph, you can use it to make predictions.If you wanted to know the estimated independent variable needed to achieve a specific dependent variable, then you would:• Find the required dependent variable on the y-axis.

• Draw a straight horizontal line across your graph until it touches the line of best fit.

• At a 90 degree angle, draw a line from that point on the line of best fit straight down, vertically, until it crosses the x axis.

• The point where your vertical line crosses the x axis is roughly the value that you would need to set your independent variable in order to achieve the required dependent variable.

Step Three: Results

Have a go at making a prediction using your line of best fit. (Don’t predict a value that you have already tested!)

• The dependent variable I want to achieve is:

• The independent variable I would need to use is:

Now try it out in real life! Was your prediction correct? How accurate is your line of best fit?

Step Four: Your Conclusion

You need to summarise your results to explain what you have found in your experiment.

• What do the results of your experiment tell you?

• Why do you think this happened?

• Was your hypothesis correct?

• Is there anything you would do differently if you were to conduct the experiment again? (Perhaps to achieve more results, more accurate results or make it easier to conduct).

Step Four: Your Conclusion

Summarise your experiment. Explain the results that were obtained from the project. Describe if they matched your expectations or not. If the desired results were not obtained, explain how and why the results are different.