0) How many properties does each piece have? There is a "correct" relevant answer, but answer this your own way.
1) How many pieces should there be in total to make the set "complete"?
2) How many colors are there?
3) How many shapes are there?
4) Now answer question 1.
5) How many pieces are missing?
6) Is there any set of the same shape with all the colors?
7) Is there any set of the same color with all the shapes?
8) What are the missing pieces?