Addition with base 10 blocks

Multiplication using a paper checkerboard

Thoughts on elementary math

http://www.mathedpage.org/early-math/early.html

Some parts can be a chore to read, but the various games/fun activity suggestions and the summary is really good on elementary math education (imho).

Base10 blocks paper printouts andother virtual manipulatives

Lessons and printouts using the base 10 manipulatives:

Base 10 Blocks printout
Base 10 Instructions
More Handmade Manipulatives Instructions
This one on using geometric shapes to learn fractions is nicely done
The Main Site