For SOSE we created our own mini water catchments. First we got a milk carton with no milk and cut the top off. Then we filled it up with sand and then put leaf litter on one and left the other one with just sand. Then we poured water over them. When we poured water over the leaf litter not much came out, but on the sand one lots came out because there was nothing blocking the water.
Below is a step by step slide show of how we went about making our water catchments.