We made a water filter.
How to make it
Cut the 5 bottles in two. Keep the bottoms. Below every bottle except one, make small holes with a punch. In every bottle there is one or two furniture. The first bottle is the bottom bottle, there is nothing. In the second bottle, first there is clay after there is coal. In the third bottle, there is sand. In the fourth bottle, there is small gravel. In the fifth bottle, first there is small pebbles after there is small pieces of wood.