We have been playing a very primitive "What Doesn't Belong?" game during M's school time lately. I draw a row of objects all the same except for one that is different either in color or in shape. Her job is to point out the one that doesn't belong.
Then I fold that row down and do another (it's less confusing when she can only see one row at a time). We do about 5 rows in each sitting. She understands the concept now and enjoys it. Any suggestions for the next level of difficulty?