Four Strokes and a Spark: teacher key

Gas and Electric Cars, grade 3 edition, written for 3rd grade. A gas engine finishes one cycle in four strokes. An electric car works another way, with a battery and a motor.

Read the book. Print this page for the key.

Questions and answers

1. What lights the fuel in a gas engine?
   • A spark plug (answer)
   • A charge port
   • A battery
2. How many piston strokes does a four-stroke engine need to finish one cycle?
   • Two
   • Four (answer)
   • Six
3. What passes a gas engine's power on to the wheels?
   • The tailpipe
   • The transmission (answer)
   • The battery
4. Which car has far fewer moving parts?
   • A gas car
   • A boat
   • An electric car (answer)
5. Where do gases go out of a gas car?
   • The charge port
   • The tailpipe (answer)
   • The motor

Words

• piston: moving engine part
• transmission: power passer
• battery: energy store
• motor: energy changer