The link above is to a website that contains numerous interactive and educational games for students at all different grade levels. There are games for math, science, geography, spelling, etc. There are even some in Spanish. There are great graphic and detailed instructions for each game so students will be engaged and able to understand what they are playing and learning.
My favorite game so far is Tony's Fraction Pizza. In this game, customers order pizza with different toppings (1/2 pepperoni, 2/5 mushroom, 1/10 cheese) and students need to show that on a pizza to serve the customer.
I highly recommend checking out this great site and trying some games with your class!