Math

DreamBox  
Math Whizz
Investigations: assessment checklists
Investigations: games for math practice - 2nd and 3rd grade
Investigations: games for math practice - 4th and 5th grade
Virtual Math Manipulatives
E-Lab 3rd Grade Math Activities

Number Sense

Math Baseball - Funbrain games to practice facts
Change Maker - Practice your subtraction skills while you calculate the change you will receive when you make a purchase
Fact Monster -practice multiplication, measurement
Magnetic Numbers - unscramble numbers and math symbols to create cool equations
Visual Fractions
Pizza Fractions -practice your fractions in a delicious way!

Geometry

Tangrams
Pentominoes
Pattern Blocks
Shape Shifter
Congruent Triangles

Graphing

Graphing Practice 1 
Graphing Practice 2 
Graphing Practice 3
Pie Graphs
Create a Graph