Here are some fun websites to work on Math.

National Library of Virtual Manipulatives
This is a great site for all grade levels (K - 12) for math. 

 

K- 2 3 and Up  
Primary Games Scribble Square A+ Math
Bobby Bear Interactive Number Square Math Games
Count the Banana's Splat Square Times Tables Game
Count Your Chickens Counter Square Penguin
Fishy Count Tables Tester Virtual Fractions
Let's Count Quick Flash Negative Numbers
Connect the Dots Table Trees Tic Tac Toe with Neg. Numbers
Make a Match Planet Math Dave's Math Tables
FunBrain Sliders Fact Monster

Telling Time

A+ Math: Mathematical Magic! Figure This!
Fastball Reaction Time Math Baseball Fraction Games
Reaction Time Lemonade Stand More Great Math Sites
Move the Hands Math Cats Binary Numbers
Stop the Clock Math is Fun Tessellation Town
Elapsed Time Geometry Algebra
Stopwatch   Tessellation Explaination
    Towers of Hanoi
    Paper Pool
The interactive Paper Pool game provides an opportunity for students to develop their understanding of ratio, proportion, greatest common denominator and least common multiple.