Students draw with a pencil on a black A4 sheet a simple mountain landscape under the moon. Colour it with oilpastel crayons and outline the mountains and moon with black crayon. Show the students that the colour of the air around the moon is lighter. Use white and yellow to brighten up blue colours, or black to darken them. Make sure your colours in the air will blend.
When colouring is finished, turn around the sheet. Draw a tree on the back, with five branches: one tho the right, one to the right edge of the paper, one to the middle above, one to the left edge of the sheet and one to the left. Branches have to be small at the end and wide near to the trunk. You've got six puzzlepieces now. Cut them out and place them on the larger black sheet. Use the cut tree to check if your pieces lie well. Pate all parts on the black sheet, exept the tree of course. Maybe you can do something fun with it?