critical thinking

Hanging a Hammer

This experiment involves balancing a hammer, a ruler, and some string. It is one of those balancing tricks that seem as though they just should not work, even though you understand the science behind them. I first learned it when I was eight years old, but it is still one of my favorites.

280

For respiration in animals, they take in oxygen and give off carbon dioxide. What about respiration in plants?

325

I took this photo at the beach. Looking at the tire tracks made me think about why car tires have treads, instead of being smooth, like racing tires. Why?

326

Genetic research suggests that this insect is neither a butterfly or a moth. What is it?

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