Pulls, Curves and Ripples: teacher key

Gravity, grade 5 edition, written for 5th grade. Gravity pulls on you, on the Moon and even on light. Follow the idea from falling things to waves in space.

Read the book. Print this page for the key.

Questions and answers

1. Which things have gravity?
   • Only planets
   • Anything that has mass (answer)
   • Only the Sun
2. Why do astronauts on the space station float?
   • They and the station are falling together around Earth (answer)
   • There is no gravity in space
   • The station is very light
3. What is the main cause of tides?
   • Wind
   • The Moon's pull (answer)
   • The Sun's heat
4. How did Einstein describe gravity?
   • A push
   • A magnet
   • A curve in space (answer)
5. When did scientists first directly detect gravitational waves?
   • 1687
   • 2015 (answer)
   • 1919

Words

• mass: amount of stuff
• orbit: a path around
• tides: sea rising, falling
• LIGO: wave detector