I wanted to do some structured activities with the pattern blocks other than simply having them build a picture with them so I made a few activity sheets. Here they are if anyone else can use them.
1. Size it up. Fill in the larger version of the shape using only the smaller ones. Once they finish the sheet, have them count. Help them observe that all of the larger shapes were built from nine of the smaller ones. Optional extension activity: leaving the first sheet intact, place a second sheet of blank paper and ask them to make medium sized shapes using only four of the individual pieces this time.
2. Colored Hexagons. Create hexagons with pieces of these colors. Once they finish have them count the pieces. Talk about 1/2, 1/3, and 1/6. Take away a piece from each hexagon. Have the child ask for the pieces back by requesting a whole, half, third, or sixth in order to rebuild their hexagons.
3. Hexagon Variations. This is mostly free play/fine motor practice. Once the child is done, ask point to two hexagons at a time and ask what is the same and what is different about the pair. Point out that one blue is the same as 2/6.
4. Pattern Path. Set this activity out along with a small toy (squinkie, lego minifigure, etc.) Tell the child the toy wants to get to the end of the path, but it is filled with water. They need stepping stones. Have them cover the pattern, and then continue it until the end. When they are finished they can help the toy hop along the path from the beginning to the end. (I haven't made a blank path yet, but doing the activity a second time with a blank path and encouraging them to create their own pattern would be a nice follow up to this one. You could make one by just tracing over this printable and leaving out the pattern I put in.)