Anne Jefferson has a new post up on stream tables. She has a super fancy new stream table, with colored beads and the ability to simulate all sorts of natural processes. I admit that I have not had the opportunity to play with such a fancy table - the only ones I've used involved play sand and a fish tank pump.
When I was a TA, we had the brilliant idea to use poppy seeds to demonstrate stream transport, which worked well... once. We put the table away at the end of the lab and a month later found a forest of poppy sprouts. Then we could demonstrate how root systems can help hold soil in place, and then we got to spend about 3 hours trying to filter a million little fibers out of the sand.
My labs had mostly upper-level non-geology undergrads. They had almost no interest in the course and were forever lobbying to remove it as a requirement (it was a little out of their area of interest). But even this jaded group loved the stream table lab. Half the class stayed around after the lab officially finished, building little dams, fiddling with the volume of water, and making their own stream beds.
Maybe I should quit my job and start building stream tables and their groundwater analogue, the ant farm with wells and hydrogeological features. Not so technically interesting, but I could totally earn a living and then I could play with them for, um, quality control.