More Fair Tests Planning experiments with the roller track

When the roller ball is released down a roller ball track like this, it hits the target ball. Roller Ball

Planning experiments with the roller track Make sure there is a raise on the target side of the track so the ball does not run off the end. Roller Ball Target Ball

Variables Look at the balls that we have. What are the variables? 10 mins

VariableValues Colour Black Multi coloured Metalic grey Material Glass Steel Plastic Size Small Large

Investigations What sort of things could we investigate with this apparatus?

Some Confounding Experiments Brass verses Steel different height Coloured marbles different targets. You are clearly much more intelligent than I am so now you can have a go.

Roller track experiments You have 10 minutes to the questions 1-5. Work together as a team and answer the questions together. You will have to use Glass marbles instead of Brass

1 High or low position Which ball would you release from the high position? Would you release the same or different ball from the low position? Explain your answer.

2 Large steel ball :-low position Which ball would you release from the high position in order to see if the height makes a difference? Explain your choice.

3 You want to see which metal ball will move a target ball the farthest Result: The brass ball moves its target ball further than the steel ball does. Does this prove that the brass ball is better for pushing any target? Why do you think this?

4 Someone plans two new experiments shown here. Result: The target ball in the first drawing is moved further than the target ball in the second drawing. Does this prove that the low position is better than the high position for moving a target ball? Why do you think this?

5 Now you want to see if the weight of a ball makes a difference to how far a target is moved. You do these experiments: Result: The target ball in the first drawing is moved further than the target ball in the second drawing. What does this prove?

What sort of relationship? Use these codes for the three different types of relationship. A – Up-Up Relationship B – Up –Down Relationship C – No relationship

Each group to prepare the answer for one of the experiments and present their answer.

What sort of relationship? (a)Which is the input variable? (b)Which is the outcome variable? (c)What sort of relationship is this A, B or C

2. Jim’s aunt says ‘when there are a lot of berries on the holly, it will be a cold winter’.

(a)What sort of relationship is this A, B or C?

3 Horrace uses a loudness meter to check the volume control of his stereo system. He measures the loudness (in decibels) for each of the volume controle. Thjese are the results (a)Which is the input variable? (b)Which is the outcome variable? (c)What sort of relationship is this A, B or C

4 A car magazine measures how much petrol is used by different size cars, all doing the same sort of journeys. These are the results. (a)What sort of relationship is this A, B or C?

5 (a)What sort of relationship type A, B or C? (b)What is the input variable?

The End Homework What sort of relationship. Page 14. Question 6

Variables Values.

Size of roller ball Size of target ball Type of roller ball Type of target ball Height of roller ball Shape of down track Shape of run out track

Your experiment. Now you have had a look at some of the problems of doing a fair test have a go at the next experiment.

What is the effect of changing the height of the roller ball on the distance the target ball moves? You have to decide which balls you will use and the steepness of your track. The target ball must not run off the end of the track.

Record your results in this table Height of roller ball (cm) (Measured from the desk) Distance target ball moved (cm) (Along the track)

Draw a Graph Draw your graph. Make sure you have labeled the axis. Give the graph a title. “Roller ball experiment” You now have done one experiment go through the lesson notes and decide on your answers to the questions page 10 & 11

What sort of relationship? What have you proved? Are there any results you are not happy with? Why are you not happy with them? What should you do about these results?

Homework What sort of relationship. Page