Ah, logic puzzles. Sometimes they seem so simple. Generally those are the times I get the answer wrong.

In this puzzle video, YouTube's Dianna Cowern (aka Physics Girl) poses a thought experiment: You're in a boat floating in a lake, holding a rock. You toss the rock out of the boat, into the water. What happens to the water level? Does the water level rise, fall, or stay the same?

As I mentioned above, this is one where I was extremely confident (and incorrect) in my answer. What's great about Cowern's answer is that she walks us through a methodology to figure out these kinds of problems, then gives us more puzzles to try. Learn up:

Note: This is one of those rare cases where the YouTube comments contain several substantive discussions (though they're still YouTube comments, so...beware).