Math Videos Go From YouTube Hit To Classroom Tool

Fifth-graders (from left) Reese Toomre, Lucas Nguyen and Michael An race through the Khan  Academy's Trigonometry Challenge. The program allows more advanced students to  move ahead, while other students can proceed at their own pace.
Fifth-graders (from left) Reese Toomre, Lucas Nguyen and Michael An race through the Khan Academy's Trigonometry Challenge. The program allows more advanced students to move ahead, while other students can proceed at their own pace.