Tightrope Walker

• 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. balanced and unbalanced forces due to gravity) in an earlier lesson.
• 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.

• Watch the pupil video here or access it via the online pupil material.

• Facilitate a discussion about gravity.
• Ask questions like these:
  • What is gravity? It’s a force that pulls everything down to the ground.
  • What is tightrope walking? The skill of walking along a thin wire or rope.
  • What skill does a tightrope walker need in order to make sure that they do not fall? Good balance.
  • What is it that keeps a tightrope walker ‘up’ on the tightrope? As long as they stay balanced on top of the rope, the rope pushes up on the walker’s feet to keep them from falling off.
• Tell the pupils that they’re going to build a tightrope.
• Distribute a set to each group.

• Have the pupils work in pairs to build the Tightrope Walker 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, introduce the test challenge.
• Explain that the pupils will take turns testing the tightrope walker's centre of gravity. They will slide the weighted bricks along the balance pole or add or remove bricks to either side of the pole to make the walker balanced or unbalanced.
• Ask the pupils to draw on their Student Worksheets (Teacher Support – Additional Resources). They should note which bricks they have placed on each side of the tightrope walker’s pole, showing how they have made her balanced and unbalanced. Remind them to indicate whether the pole is longer or shorter on one side.

• Gather the pupils together to review and discuss what they have built.
• Ask questions like these:
  • What did you notice about the tightrope walker's balance and how it changed when you moved the pole?
• Explain that gravity is the force that pulls the weighted bricks down the tightrope walker's arms or pole. This helps to equalise the weight on both sides so that she can maintain her centre of gravity and not be pulled down, which would make her fall.

• Ask the pupils to explore their centre of gravity:
  • Have them stand on one foot, with their other foot close to the ground. Tell them to start raising the foot that is close to the ground to see how long they can stand before losing their balance. Have them try this with their arms at their sides and then again with their arms open wide. Which is easier?
  • Choose 1-2 pupils and ask them to stand on one foot, with their other foot high off the ground. Then have them try this while holding a book out to their side.
  • Ask which way they felt the greatest pull of gravity and which way felt the most balanced.
• 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 the pupils 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 centre of gravity, balanced and unbalanced.
• 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 and explain 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

• The small wheel on the bottom of the tightrope walker may be hard to find. It’s in the tray with the black and grey elements.
• The small wheel on the tightrope walker is very difficult to remove. It does not need to be taken apart, so tell your pupils to leave these elements assembled. Make sure that your pupils never try to separate elements with their teeth!
• The length of the model's axles is measured in LEGO^® studs. Demonstrate how to measure the 16-stud axle by lining it up with a 16-stud white plate, highlighting that the axle is 16 studs long.

Simplify this lesson by:

• Having the pupils perform a test where they place the same bricks on each side of the tightrope walker and then replace them with different bricks to observe the pull of gravity

Increase the difficulty by:

• Challenging your pupils to make a centre of gravity game in which each pupil chooses the left or right side of the pole, which is centred to the tightrope walker
  • The pupils take turns choosing 5 brick elements, using them to try and tilt the tightrope walker to their side
  • The winners will have chosen and attached the heaviest elements

(Note: This will require additional time.)
To incorporate the development of maths skills, have your pupils work in pairs to write word problems about balancing the tightrope walker. Then ask them to solve each other’s word problems.

National Curriculum Maths: ACMNA029, ACMNA029, ACMNA030, ACMNA030, ACMNA031, ACMNA031, ACMNA032, ACMNA032