This is an activity I knocked together for my 2nd graders: I taught a lesson on recognizing "landmark" subtraction and addition facts, and wanted my students to recognize how to double and half numbers quickly and easily. It comes in two levels of challenge: halving and doubling numbers 2 - 20 and halving and doubling numbers 20 - 36.
Players take turns selecting a card from the deck: they double and halve it, and then choose a space with one of those two numbers. First one to get four in a row wins.
It's a pretty good game, lots of fun and I'm sure it will go nicely with the kids who are weak or need challenge.....
"All killer, no filler...."