Use a fitted sheet for the bottom! (Even nurses use fitted sheets these days!)
Lay your top sheet over so that it hangs equal on both sides
You have to lift up the mattress so that you can neatly tuck the sheet under the mattress.
Folding the first corner
Folding the second corner!
Making the bed with both the bottom sheet and the bed spread.
There you have it, a tidy bed for your kid to mess up!