Across
- 2. bones working together create this system
- 4. substance inside your bones
- 5. planet closest to the sun
- 9. the Milky Way is this type of galaxy
- 10. bouncing light
- 13. a thin protective covering on the surface of the eye
- 14. the movement of the Earth on its axis
- 15. an explanation of how or why something happened
- 17. this force keeps us anchored to Earth
- 18. the path that a planet follows around the sun
- 19. Sound vibrations travel through the air in _____.
- 21. animal that has hair or fur and breathes with lungs
Down
- 1. the movement of the Earth around the sun
- 3. Light can easily travel through ________ materials.
- 6. this animal is covered with plates or scales
- 7. a meteoroid that enters Earth's atmosphere and burns
- 8. the highness and lowness of sound
- 11. Light can only travel in ______ paths.
- 12. an animal that has a backbone
- 16. This joint is found in your knees.
- 20. Sounds travel best through _______.