Games with balls are some of the most common activities for second graders. Use a large utility ball to play dodgeball. Break the class into two large teams. Play kickball outside and teach your students the rules of baseball at the same time. Play center jump ball, in which two students roll a ball to each other, while a student in the middle tries to jump over it. If he fails, he switches place with a roller.
A large parachute provides physical activity and teaches cooperation to students. Play cat and mouse, where one student crawls around underneath the parachute, while another students crawls around on top trying to catch him. Or, place a variety of balls on the parachute and see how high the group can launch them. Have the students lift the parachute as high as they can, pull the edges down and then sit in a circle inside the parachute. Wait until the parachute caves in around the students.
Running games give second graders the cardio exercise they need. Play chase, a version of tag, in which half the class gets a 10-second head start to run into the playground. The other half is "it," and must tag all the chased players.
Try a version of Simon says, while players skip with skipping ropes. It requires stamina and coordination. Play follow the leader, as one students winds his way through an obstacle course while the rest of the class follows. Organize a jumping competition, where students compete for the longest and the highest jumps.