Push Car Derby

• Review the online pupil material. Use a projector to share this material with your pupils during the lesson.
• Make sure that you have covered the relevant concepts (i.e. push, pull, friction, measuring distance) in an earlier lesson.
• Set up a racetrack by clearing an area of smooth floor at least 1 meter long where the pupils can test their cars. Use masking tape to mark the start line.
• Consider the abilities and backgrounds of all your pupils. Differentiate the lesson to make it accessible to everyone. See the Differentiation section below for suggestions.

• Before showing the video, ask these questions:
  • How can you make a car move without using a motor?
  • Have you heard of a push car derby?
• Watch the pupil video here or access it via the online pupil material.

• Facilitate a discussion about the forces the pupils noticed in the push car derby shown in the video.
• If the pupils need a little guidance, help them by asking:
  • What made the cars move fast or slow? Push strength, hills, friction.
  • What would happen if the people let go of their car? It would keep rolling.
  • What can slow a car down? A brake, friction.
• Tell the pupils that they’re going to build a push car and a spring launcher.
• Distribute a set to each group.

• Have the pupils work in pairs to build the Push Car model. Tell them to take turns, one partner searching for the bricks while the other builds, switching roles after each step has been done.
• You can find building help in the Tips section below.
• When the pupils have finished building, have the teams place their launchers at the start line.
• Tell the pupils to measure the distance travelled each time they launch their car. They can use a ruler, or they may use manipulatives that can measure.
• Give your pupils these instructions for the test challenge:
  • Push or pull the spring forwards and hold it in place. Highlight that this retracts the spring and changes its shape.
  • Place the car next to the Minifigure.
  • Tip: The car goes the farthest if you roll it back so that it is touching the yellow pushing brick before you let go of the spring. Demonstrate this to your pupils.
  • Release the spring and watch the car go.
  • Try pushing with the yellow brake on, then remove it and see how far the car goes without the brake.
  • Measure 3 tries with the brake on and 3 without it. Place another Minifigure with a chequered flag at the car's stopping point after each trial. If the previous distance is beaten, move the Minifigure to mark the new stopping point; otherwise, leave it where it is.
• The pupils can record the results of their trials on their Student Worksheets (Teacher Support – Additional Resources).

• Gather the pupils together to share what they have built.

• Ask questions like these:

  • What did you notice about how the brake affected how far the car moved?
    Explain that the brake pushes against the wheel of the car and slows it down.
    The floor also pushes against the wheel. These forces are called ‘friction’.
  • Why do you think the car went farther in some of the trials than in others?
  • What did you notice about pushing as a force?

• Have the pupils look at the arrows on the launcher.

  • Why are there 2 arrows on the launcher?
  • What are they indicating (i.e. push/pull)?

• To explain friction further, have the pupils wave their hands in the air. Explain that it’s easy because there's low friction. Then ask them to drag their hands across their desks. Explain that the harder they push down, the harder it is to move their hands. That’s because there's high friction. The brake on a car works the same way.

• Ask your pupils to line up all their launchers and have a push car derby. Whose car goes the farthest? Why?
• Allow time for the pupils to disassemble their models, sort the bricks back into the trays and tidy up their workstations.

• Ask guiding questions to encourage them to ‘think aloud’ and explain their thought processes and reasoning in the problem-solving decisions they have made when building their models.

Observation Checklist

• Measure your pupils’ proficiency in describing how various forces affect how a bigger push or pull makes things speed up or slow down.
• Establish a scale that suits your needs. For example:
  1. Requires additional support
  2. Can work independently
  3. Can teach others

Self-Assessment

• Have each pupil choose the brick that they feel best represents their performance.
  • Green: I think I can describe what ‘push’ and ‘pull’ mean.
  • Blue: I know I can describe what ‘push’ and ‘pull’ mean.
  • Purple: I can describe what ‘push’ and ‘pull’ mean, and I can help a friend to understand, too.

Peer Feedback

• In their small groups, have the pupils discuss their experiences working as a group.
• Encourage them to use statements like these:
  • I liked it when you…
  • I'd like to hear more about when you…

Model Tips

• This is a challenging model. If you see that the pupils are making mistakes, point them out so that the errors don’t compound as they go on. After 20 minutes, most pupils should have at least completed the launcher. it is best to stop the pupils building at the 20-minute mark to give them time to experiment. If they haven’t finished building the car, they can push a marker or a ball of paper.
• Before the lesson, build this model yourself. Keep it as an example to clarify to the pupils how their models should work.
• When launching the car:
  • One partner should pull forwards on the yellow arrow and hold the launcher in place.
  • The second partner should place the car next to the Minifigure. To maximise the transfer of energy, ensure that the car is touching the brick that will push it.
  • Release the spring to launch the car.

Simplify this lesson by:

• Having the pupils practise pushing just the base of the car, without the yellow box

Increase the difficulty by:

• Challenging your pupils to rebuild the launcher, changing the placement of the spring to see if it improves the launcher's performance (i.e. Does the launcher even need a spring?)
• Challenging the pupils to design new cars that will roll even farther

(Note: This will require additional time.)
To incorporate the development of maths skills, have your pupils use different units of measure to record the distance their car travels, and then compare them. They can, for example, measure how far their car travels in LEGO^® bricks, LEGO studs, shoes, or another creative unit of measure.

ACMMG019
Measure and compare the lengths and capacities of pairs of objects using uniform informal units