This is a very simple but fun game I use with my 1st grade class. I divide my class in half (my class was previously divided into the Panthers and the Dolphins). One child from each side comes up to the front of the room (where I previously placed the 2 bells on a desk) and stands in front of their bell on their side. I call out a math problem and the first person to ring the bell calls out the answer and that team gets a point. The kids just love it. You can also just put the math problems on cards and hold it up.