Make various shapes of various sizes and colors. Using a pre-determined number of shapes, have your students make pictures out of them. Once they have their pictues as they want them, have them glue them to paper.
Remember, they are only allowed to have a certain number -whatever you choose. For example, here is James' picture for the number 8. They can play this game over and over, with different amounts of shapes. This gives them an idea of the amount of various numbers of objects. They learn, for example, what 8 looks like. It also increases their estimating skills.