Hammer, Feather, Moon: teacher key

Pushes and Pulls, grade 3 edition, written for 3rd grade. On the Moon, a hammer and a feather fell together. See why, and learn what weight, mass and simple machines are.

Read the book. Print this page for the key.

Questions and answers

1. A hammer and a feather are dropped together on the Moon. What happens?
   • They fall at the same rate (answer)
   • The feather lands first
   • The hammer floats away
2. What is weight?
   • How much stuff a thing is made of
   • The pull of gravity on a thing (answer)
   • How fast a thing falls
3. Why would a person weigh less on the Moon?
   • It has no air
   • It is far from the Sun
   • Its gravity is about one-sixth of Earth's (answer)
4. Which force works across a gap?
   • Gravity (answer)
   • Friction
   • A hand push
5. A small push has to do a job that needs a big force. What could help?
   • A feather
   • A lever (answer)
   • Drag

Words

• gravity: pull toward Earth
• drag: air slowing things
• mass: amount of stuff
• weight: gravity pull
• lever: simple machine