Simple Machines — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. A seesaw at the playground is an example of a lever.
A seesaw is a lever because it is a bar that pivots on a fulcrum to lift and lower people on each end.
2. A pulley helps you raise a flag to the top of a pole.
A pulley at the top of a flagpole lets you pull the rope down to raise the flag up.
3. An axe blade pushes wood apart because it is a wedge.
An axe blade is a wedge because its thin, sharp edge splits wood apart when force is applied.
4. A jar lid works like a screw because it has spiral grooves.
A screw has spiral threads that dig into materials, holding them tightly together.
5. A doorknob turns around an axle to open the door.
The axle is the rod at the center of the wheel that allows it to spin and move the bicycle forward.
6. Sliding a heavy box up a ramp uses an inclined plane.
A slide is an inclined plane — a flat, sloped surface that lets you move from a high point to a low point.
7. A crowbar helps pry open a lid by acting as a lever.
A crowbar is a lever because you push down on one end to pry up an object on the other end, using a fulcrum point.
8. Simple machines do not reduce the total work, but they reduce the force needed.
Simple machines help by changing either the direction or the amount of force you need to apply to complete a task.
9. A nail is a type of wedge that holds pieces of wood together.
A doorstop is a wedge because it uses its sloped shape to push under the door and hold it in place.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
Wheel and axle
→ Doorknob that turns to open
Ramp to a building entrance
Screw
→ Spiral inclined plane on a rod
Spiral inclined plane on a rod
Inclined plane
→ Ramp to a building entrance
Seesaw on a playground
Lever
→ Seesaw on a playground
Doorknob that turns to open
A wheel and axle is like a doorknob, a screw is a spiral inclined plane on a rod, an inclined plane is like a ramp, and a lever is like a seesaw.