Some Useful Web Based Tools for Math for Elementary Education

Conceptua math: fraction tools

Thinking blocks: Modeling word problems and operations with fractions, ratios, and whole numbers

Math Playground tools including Cuisenaire rods,  pattern blocks, geoboard, a function machine, transformations, a pretty good spinner, fraction-decimal-percent scales, an algebra balance scale, transformation tool, long division... rather a lot of useful stuff!

In particular, I've decided I rather like professor x and the factorbots (though I don't know how to make it into a good lesson)

Multiplication blocks is great for factoring

Shodor interactive

Animal Rescue is pretty good for negative number visualization:

The Math Cats tessellation pictures are kind of fun
This looks like a useful list too:

I also like the games at Manga High:

and Lure of the Labyrinth: I've decided the first set of puzzles (the cafeteria puzzles) would be good when working with ratios. (maybe)

Glencoe has some pretty good virtual manipulatives:

These are good virtual base 10 blocks
the other virtual manipulatives look promising too:

good number line and a good base 10 blocks app

More virtual manipulatives

Pretty good base blocks activities

Shape sorter for geometry properties

Dreambox. I like the third grade number line tools (though they need a little instruction)

 I like this decimal and fraction sum estimator