I'm not convinced by 2 of the answers to their 5 question pop quiz:

> Q: How much does the Earth weigh? A: 1,000 trillion metric tonnes

But isn't asking the weight (and not mass) of a planet fairly meaningless?

> Q: How do aeroplanes stay up? A: The upward lift of a plane is created by its curved wings

Isn't the dominant component due to downward deflection of oncoming air?