1. Where did the atmosphere come from? By the end of the lesson
you will understand how oxygen led to a revolution in the
development of life
2. But first a quick bit of Maths!
How many hundreds in a thousand?
How many thousands in a million?
How many millions in a billion?
3. 4. 5. 6. 7. 8. 9. Where did the atmosphere come from? By the
end of the lesson you will understand how oxygen led to a
revolution in the development of life
