This week, I had the pleasure of a delightful conversation with Kim Aaron, a friend who works at NASA's Jet Propulsion Lab in California. We were talking about the Pool, Boat, and Anchor videos, and Kim had some wonderful ideas. If you are not a member (of course you could become a member today) and have not seen the videos, we started by imagining a boat floating in a pool of water. In the boat is an anchor. The challenge was: If you drop the anchor into the water, will the water level rise, stay the same, or fall.

I won't spoil the challenge by putting the answer here, but I will share some additional challenges that came from my conversation with Mr. Aaron.

1. What if the boat had a small lifeboat onboard? If you put the lifeboat into the water, would the water level rise, stay the same, or fall?

2. What if you had a large piece of cork that weighed as much as the anchor? If you threw it overboard, would the water level rise, stay the same, or fall?

3. What if you had 100 pounds of water in the boat, and poured that overboard? Would the water level rise, stay the same, or fall?

And for a real challenge:

4. In the original challenge, compared to a point on the ground outside the pool, when you drop the anchor overboard, will the boat's level rise, stay the same, or fall? To answer this, you have to consider what will happen to the water level, what will happen to the boat's level in the water, and which will have the larger effect?

You are welcome to leave your answers and/or further questions as a comment.