Students are divided into two even teams, and each student gets a number. There will be two students with each number (one on each team).
Call out a question, and then state a number.
The student with that number to stand up first and call out the answer correctly gets a point for their team.
If there is a tie, they play rock, paper, scissors to see who wins.
Hand out numbered index cards to make sure they remember their number. Have them switch numbers a couple of times during game play to square off against someone else.
If you like, here is a Random Number Generator. Just type in the number of students per team.