This is another project idea from Malke Rosenfeld. The basic idea is this – students create their own versions of an attribution matching game. In these games the idea is that each card in the game is unique, but that it has traits (like colour, shape, type, etc…) in common with other cards, and the objective of the game is usually to try and create matches based on those attributes.
Read her blog post to get a more complete description of how this project works.
Math Thinking 
The original activity had me and my daughter creating our own sets of matches by tracing geometric shapes and making both cards in each set as ‘same’ as possible. It was a good challenge for a 6 year old!