Grade 4 · Science · Unit 7 of 9
Gears, Levers & Motion
How mechanisms change speed, force and direction
What your child practises
Rotary, linear and back-and-forth motion, how gears of different sizes change speed, how pulleys and levers change force and direction, and how a bicycle moves.
Ontario Curriculum expectation: D2.3, D2.4, D2.5 · how mechanisms transfer and change motion, speed, direction and force
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
A wheel with 10 teeth drives a wheel with 30 teeth. Compared to the driver, the driven wheel turns…
⚙️- three times faster
- three times slower
- twice as fast
- at the same speed
Show answer
three times slower
Hint: It has three times as many teeth.
Question 2
A linkage joins levers so that moving one makes another move. What can linkages do?
🔗- make a machine disappear
- change the direction of motion
- stop all motion
- turn forces into light
Show answer
change the direction of motion
Hint: Windshield wipers use linkages.
Question 3
Put the steps of how a bicycle moves in order.
- 🚲the bicycle moves forward
- ⛓️the pedals turn the chain
- 🛞the chain turns the back wheel
- 🦵your legs push the pedals
Show answer
your legs push the pedals → the pedals turn the chain → the chain turns the back wheel → the bicycle moves forward
Hint: Your legs turn the pedals, the pedals turn the chain, the chain turns the back wheel, and the bike moves.
Question 4
A longer wrench makes it easier to turn a bolt because…
🔧- it weighs more
- you apply the force farther from the turning point
- bolts like long tools
- it is shinier
Show answer
you apply the force farther from the turning point
Hint: A longer lever means less effort.
Question 5
A sewing machine needle going up and down is…
🧵- rotary motion
- rolling motion
- reciprocating (back and forth) motion
- no motion
Show answer
reciprocating (back and forth) motion
Hint: It moves back and forth in a line.
Question 6
A gear with 10 teeth turns a gear with 20 teeth. The small gear makes 8 full turns. How many turns does the big gear make?
- 4
- 3
- 14
Show answer
4
Hint: The big gear has 2 times as many teeth, so it turns 2 times slower. Divide 8 by 2.