Playing with light and shadows is great! One idea is to trace shadows and then make a really nice picture out of them. Lie down in a place where the sun is shining with a piece of paper, a pencil and some toys. Turn towards the sun and make sure that the shadow of the toy falls on the sheet. When this happens, draw the contours of the shadow with your pencil. Then you can colour in the whole picture. You can play this game with different toys.   

And if the sun is not shining too brightly, you can also use a floor lamp or a torch.  

You can find more activities to do at home at