1
2
3
4
5
6
7
8
Across
- 1. How often something happens in a given time
- 4. A tiny particle of light energy
- 5. A quick back-and-forth movement
- 7. The central part of a cell that controls its activity
- 8. The bending of light as it passes from one material to another
Down
- 2. A chemical change when substances interact
- 3. Vibrations that travel through the air and are heard by ears
- 6. To write down information for later use