7 класс 
Task 1
Questions to the text on p. 69 ex 7 (A)
Answer to the following questions in your ex. books!!!
1. What can you burn without oxygen?
2. What the first thing you should do to find out how much oxygen is in the air?
3. And what the second thing ?
4. Where do you mark the level of water?
5. What can you find after this experiment?