The smaller cards fit perfectly in each section of the fraction circle. For example, put the smaller cards on each of the sections. Keep the fraction circles whole to make this activity easier to handle.
For example, put 1/2 on each section of the fraction circle with 1/2 sections. Do the same for the other circles. Start with the largest fractions first.
The second set of bigger cards are used to match the cut up fraction circles. Use these cards to represent the combination of the fraction circles. For example, 2/3 is matched with two 1/3 pieces of the fraction circle.
Here are some other ideas for fractions.
Check out Making Fractions from your local library
Google Book Search excerpts -Fabulous Fractions