Imagine a toy car rolling off the same ramp onto four different floors: carpet, wood, sandpaper and tile. Which floor do you think will stop it soonest?
Today we will find out fairly, and we will measure with real care.
Our question is: Which surface slows a toy car the most?
Look at the four surfaces: carpet, wood, sandpaper and tile. Whisper to your partner which one you think will make the car roll the shortest distance, and say why. Then we will share a few ideas with the class.
We will plan a fair test so only one thing changes. Five cards appear on the board: surface, distance the car rolls, ramp height, the car, starting point. Call out where each belongs: Change, Measure, or Keep the same.
The shared plan stays on the board. On your Investigation Journal page, write only three quick things: one extra keep-the-same your group will check on every run (for example how you release the car, or how you place the metre stick), the order you will visit the four surfaces, and your prediction.
Which surface slows a car most?
Watch the first teacher run carefully before you begin.
Then work with your group:
- Set your ramp on two identical books (the class height on the board) and mark one start line.
- Visit the shared surface stations in the order your group chose. Change only the surface under the car.
- For each surface, release the same car from the same start three times with no push.
- Measure from the start line to the front of the car in centimetres each time. The ramp part is the same every run, so a shorter total still means that surface slowed the car more.
- Put the three distances in order — shortest, middle, longest — and write the middle number on your Investigation Journal before you move on.
Take your time — careful measuring is the science today.
You should already have three distances and a middle value for each surface you finished on your Investigation Journal from the runs.
Take a few quiet minutes to check: same units (cm), three fair tries each, numbers ordered correctly before the middle value, and no invented readings. Keep what you measured separate from what you think it means. Finish any missing fair trial now if a car left the surface earlier.
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