A.H.
We have our son go to www.funbrain.com or www.primarygames.com Both of those he played in school. Another safe website for kids that has educational and just fun games is www.kidzui.com it is a compilation of websites that are all safe for kids. (There is one website 'A games' that has things of a sexual nature we found out the hard way and on kidzui those games are blocked and only the positive kid friendly games are allowed)
We also bought the JumpStart World game and our son loves it (he's going into 2nd grade too). It is a little expensive because in the store you only get the starter pack and have to buy additional lessons but it wasn't bad. I think total it cost 80-90 for all 12 lessons and in each lesson there are about 20 activites the child has to do (reading, math, social studies, science) and with each activity they try to earn a gem and with the gems they can buy stuff in the world and there are missions they go on, races, art stuff, they can buy a pet to take care of .... very in depth. My son has had it for a couple months and is on lesson 4 and plays it quite a bit, some of the activities are pretty tough but are made fun. They are all done in game form. Anyways it's really cool and worth the money to keep they focused at their level.