Daily Challenges

Pulling a rope until it rips in half is the newest strength-training fad. Is it easier to pull against a wall or a friend?

Just because it looks like all the steps are valid doesn't mean that they are. What went wrong in this "proof"?

Buoyancy will always bring air bubbles to the surface, but do all bubbles rise at the same rate?

Calcdoku is a game of logical reasoning. What numbers will successfully fill the grid?

Some 3D shapes have similar cross-sections. Can you compare how the cross-sections change to identify the solids they come from?

Paleontologists have found the fossilized tracks of giant bugs around the globe. Why don't we see human-sized bugs today?

Random sampling allows for thinking about an entire group without looking at every individual.

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