Hosting a tea party uses math skills. So does building towers. Preschoolers are wired to learn such premath concepts as comparing when they play. Just provide the materials.

Getting in Shape. Cut construction paper into squares, rectangles, diamonds, and triangles and fit them together to make new (bigger) shapes. Or go 3-D and build shapes with blocks. Let your preschooler make up his own names for his many-sided shapes.
Benefits: Spatial skills and creativity
How Big? You don't need to dig out a ruler or a measuring tape -- even a piece of string can size up your child's dollhouse. Help her use the same string to compare the house's height with her biggest stuffed animal.
Benefits: Comparing and spatial skills
Pick-Up Artists. Next time you're putting away the tea-party toys, tell your preschooler you'll clean up the toy foods while he picks up the plastic plates and utensils. Then let him assign what each of you will pick up next.
Benefits: Planning and matching categories of things (not to mention a clean room!)
Making Patterns. Little kids love to make trains out of playing cards, cars, or pillows. Ask your child why she put the red pillow next to the green pillow. Did she group them by size or alternate them by color? Suggest a different way she could arrange them.
Benefits: Sequencing -- a premath and prereading skill -- and creativity.

Stumble Upon Facebook Del.icio.us Google Yahoo Digg it