Here's the concept: two matching puzzle cards will each show, say, one object to make a match. For the next two matching puzzle cards, one will show one object and the corresponding card will show two objects (similar backgrounds and such will also help the child connect these cards). The next two matching puzzle cards will each have two objects. The pattern continues up to ten. This way the child not only grasps how many the number is, but also what numbers come before and after that number.