ABCya has games for math, reading, letters, strategy and all kinds of random information. The games range from PreK-5th grade. The games can be played on a laptop or Iphone.
Room Recess has similar games to ABCya.
This website covers a lot of different skills and subjects, mostly around math and reading.
PBS has all kinds of apps, stories, and games for elementary aged kids. Their game section covers science, math, reading, creativity, literacy, music, and social emotional.
This is a good one for young children learning to read and do math.