Prefix speech bubbles. Divide the students into teams. Give each team a set of laminated speech bubbles (attach to popsicle sticks for easier handling). Tell students a base/root word and they have to hold up the speech bubble for the prefix that would go in front of the base/root word. All members of the team have to agree with the bubble selection. If they get it correct, the team gets a point. The team with the most points at the end is the winner.