Martha Speaks

From site: 

Martha is here to help kids learn lots of new words as they play.

Each game on our site introduces a whole bunch of new words. The more kids play, the more words they’ll hear. Play along with them if you can, or talk to them about the games later so they have a chance to practice the new words they’ve learned.

Before you know it, your kids might come to a consensus about which game is their favorite – especially if the weather forecast is for precipitation.