Math Resources

Worksheets for shapes, matching, equivalence, more, and less
To recognize shapes and practice matching, you can either use ready-made worksheets or workbooks, or make some of your own.
If you make your own, you can just draw three circles on a page and then 2-5 triangles on a page, and ask the child to match each circle with a triangle by drawing a line from shape to shape. Vary the shapes and the amounts. Sometimes the amounts should be equal, sometimes not.
Another variation is to ask the child to draw. First make some sticks, circles, squares, or other shapes on a page, and encircle them. Make for the child a big "bubble" to draw in, and ask the child to draw either the same amount, one more, or one less.
Also have your child practice writing numbers on paper.

You can find lots of different kinds of basic kindergarten workbooks at LearningThings.com. You don't really need anything too fancy to practice these concepts, so workbooks from many different publishers can work equally well.
Singapore Math's EarlyBird Kindergarten math is praised a lot. Dorling Kindersley's kindergarten math workbook is of good quality as well.

There are of course several fine websites that have free worksheets for kindergarten math, such as:
Kidzone.ws kindergarten math worksheets
Maths is fun kindergarten worksheets
Kindergarten math worksheets from About.com