Things that make you go "Hmmmmmm"

We started our unit "My Earth" a couple of weeks ago and planted bean and pumpkin seeds in three different 'earth materials'.  Soil.  Pebbles.  Sand.  For two days nothing happened--just kinders watering faithfully and claiming that "their" seed was growing.  Then we got or first sprout.  In the sand.  Things are not going as they are supposed to....