Gears and Power: teacher key

Gas and Electric Cars, grade 6 edition, written for 6th grade. Follow a gas engine's power through the crankshaft and gears to the wheels. Then see how an electric car uses a motor and a battery.

Read the book. Print this page for the key.

Questions and answers

1. How many piston strokes finish one cycle in most gas engines?
   • Two
   • Four (answer)
   • Six
2. What does the crankshaft turn into spinning motion?
   • The up-and-down motion of the pistons (answer)
   • The tailpipe
   • The charge port
3. What are gears used to do?
   • Charge a battery
   • Increase speed or force (answer)
   • Light the fuel
4. Which batteries do most electric cars use, as of November 2026?
   • Lithium-ion (answer)
   • Gasoline
   • Steam
5. When an electric car slows down, what can its motor act as?
   • A piston
   • A tailpipe
   • A generator (answer)

Words

• cycle: round of steps
• crankshaft: spinning engine part
• generator: makes electricity
• friction: rubbing