A student places a row boat in a swimming pool, loads the boat with a number of bricks, and rows to the center of the pool. Once there, the student carefully notes the water level, throws the bricks into the swimming pool and once again notes the water level. What had happened to the water level in the pool?

The water level would go down. When they're in the boat, the bricks displace their weight in water. When they're tossed overboard, they only displace their own volume. Since they're denser than water, their weight in water takes up more space than the bricks themselves.