Across
- 2. it is a green stain that comes from the grass
- 4. scientists make sure they only change one variable in all experiments
- 7. plants breathe it out
- 8. it is how plants grow
Down
- 1. we drink it and we also need it to live
- 2. plants inhale it
- 3. it travels in a straight line
- 5. it causes heat in our body and it also has something to do with our breathing
- 6. the control center of the cells
- 9. you may put this in your tea or coffee