Pbs kids games such as Daniel Tiger's Neighborhood and Curious George are great for showing them basic math skills, colors, letter recognition, sorting, and fine motor skills by moving the mouse in the proper direction.
Visit such free online game websites as Room Recess, and you will find fun reading games like Monkey in the Middle and Sight Word Safari that help kids improve their reading and word recognition.
Strategy games like Monster Tower Defense, Dungeon Knight, Klondike Solitaire, and Sweety Mahjong are fun for the kids, free without requiring downloading, and teach kids problem-solving.
Jigsaw puzzles are a great problem-solving exercise for kids, and it's fun to put together larger puzzles with friends. Puzzles can also teach children perseverance and teamwork!
The objective is to fill a 9 x 9 grid with digits so that each column, row, and each of the nine 3 x 3 subgrids that compose the grid contain all of the numbers from 1 to 9.