Genius Boxing
http://www.mrnussbaum.com/geniusboxing.htm

"Genius Boxing" is a program that allows students to compare numbers. In the middle grades, students are using inequality symbols to compare numbers and are writing sentences with inequalities. This program allows students to practice this skill in a fun and engaging manner. Students are boxing against a famous opponent (like Bill Gates or Albert Einstein), and can score a knockout by answering questions correctly. Incorrect answers result in a punch from the opponent. Students can win the game by successfully knocking out all challengers, but to do so will have to answer increasingly difficult questions.