Trickle Down Theory

Ethan is very observant and he intently studies things so he can understand how they work. He discovered that if you place sand on the top, that it will trickle down to the other levels below.

I reminded him that this is what happens when he throws sand at Grampy, it trickles down to his feet.

He reminded me that it is the same principle as the diaper trickle down theory.