We talked about erosion in class today. Because it's St. Patrick's day on Sunday, I brought in a shamrock plant for the kids to look at as part of the erosion demo. Some of the questions I chose to not to answer included:
"Why is there only one flower?"
"Does it smell like anything?"
"Why is the underside purple?"
"Why doesn't the flower look like clover?"
Well... I don't have all the answers. And technically, the shamrock is an oxalis plant and looks like this.
And they wanted to know why I used coffee grounds instead of sand, or actual dirt. And I really didn't want to get into the specifics of hydrophobia with them, and how the coffee grounds were going to mimic wet sand and suck up the water easily and move the way I wanted them to.
However. They got the picture. Coffee grounds, in a pile, at the top of a tilted cookie sheet, when mixed with "rain" from a watering can, would "erode" down the side of the cookie sheet hill. But the dirt in the pot, even when the pot was tilted on it's side when it was "raining" wasn't really going anywhere, because there were roots holding it in place.