Apply knowledge and skills related to wheels and axles, friction, ratchets and gears, measuring, and fair testing.
Jack and Jill have made a luxury double-seater cart, but it is very heavy to push up the hill.
Can you design a way to stop the cart from rolling back down the hill when they stop to catch their breath?
Design and make a vehicle that:
• can carry at least 50 g (≈ 1.75 oz) (or approximately 1 weight brick)
• has a safety feature that does not prevent the vehicle from rolling forwards
- Make a sketch of the idea you designed and made.
- Label the three most important parts, explaining how they work.
- Suggest three improvements.
Suggested Model Solution
Note: You are advised not to share this image with students.
Fair testing and Fun
Can the cart carry the weight of at least one weight brick?
Test to see, then add more weight. What are the criteria for success?
The cart should not break and the load should not rub against the wheels, etc.
Does it roll freely?
Set the hill at any slope angle you like, (e.g. 30 cm [≈ 12 in] high at one end of a 1 meter [≈ 1 yard] plank) and run the cart forwards down it. The further it rolls along the floor the better.
Does the auto stop feature work?
Turn the cart around without touching anything on board so it faces backwards down the hill. Let go! Does it stay still? Keep increasing the steepness until the cart slips. The steeper you can go before it slips, the better.
How safe and comfortable is your luxury cart?
Make two play dough riders with very smooth skin. Place them gently on the cart in whatever seats are supplied. Let the cart run down the hill until it stops. Now check the riders for bumps, cuts, and bruises – the less, the better.
How will they survive bumping over an all-terrain course?
Would your cart be a good ambulance?
Harness wind energy to help push the cart uphill. Make sure that the auto stop will stop it rolling down the hill again if the wind stops.
All Terrain Cart! Can you find a way to make the cart climb over rulers and maybe even pencils that are put in its way on the hillside?
Create a means of storing things on board the cart.
Students will be able to apply the knowledge and skills of:
Wheels and axles
Ratchets and gears
Predicting and measuring
Applying principles of fair testing and product safety
9686 Simple & Powered Machines Set (two students per set recommended)
A meter rule or measuring tape
A plank to make a sloping hill
Card and tape to make a runoff ramp at the bottom of the hill
A desk fan to provide the energy for wind-assisted carts
Optional: playdough for making test pilots
Disciplinary Core Ideas: Physical Science
MS-PS2 Motion and Stability: Forces and Interactions
Cause and effect
Systems and system models
Structure and Functions
Stability and change
Science and Engineering Practices
Asking questions and Defining Problems
Developing and using models
Planning and carrying out investigations
Analyzing and interpreting data
Using mathematics, Informational and Computer
Technology, and computational thinking
Constructing explanations and designing solutions
Engaging in argument from evidence
Obtaining, evaluating, and communicating information
Common Core Mathematics Standards
7.RP.A / 6.NS.B / 6.EE.C / 7.EE.B / 8.EE.B / 8.F.B / 6.SP.A
Common Core English Language Arts
SL 6.1 / 6.2 / 7.1 / 7.4 / 8.1
RST 6-8.3 / 6-8.4 / 6-8.7
WHST 6-8.1 / 6-8.7 / 6-8.8 / 6-8.9