The purpose of this activity is to learn how the oxygen cycle and carbon dioxide cycle are interdependent within an ecosystem.

- Small, clear wide mouth jar/or large beaker
- Water
- Leaf
- Magnifying lens
- Sunny location or goose neck lamp

Teacher Demonstration 2 (Multiple day 1-3 observation)

- Elodea plant - pet store
- Water
- Deep container
- Clear funnel
- Test tube
- Sunny location or goose neck lamp

Student Experiment

- Goggles (all students)
- Aprons (all students)
- 600 ml beaker 3 per group
- Water
- Eye dropper 1 per group
- Bromothymol Blue (BTB)
- Plastic straws (1 per student)
- Elodea plants
- 3 test tubes ( with capability of being sealed - culture tubes with caps if available, if not use corks or aluminum foil and tape) per group
- Test tube holder (clamp)
- Test tube rack