I have a couple of games I used to play when I was in school myself--and used for my summer camps.
1. Red Rover
A. Split the students into 2 teams, holding hands.
B. Have those from Team 1 call out "Red Rover, Red Rover, let (Team 2 student's name) come over."
C. The named student from Team 2 must run across the field and through a pair of hands.
C 1. If the hands let go, Team 2 student can take one member from Team 1 to his side.
C 2. If the hands hold on and don't let go, that Team 2 student is now part of Team 1.
D. The game continues until there's either 1 or none left from one of the two teams--or whenever you see fit to stop it.
2. Octopus
A. Make 2 lines across a field (like a large rectangle from Panic's "Mr. Crocodile" game) and have 1 student in the big center space.
B. All the other students are behind one of the lines. They must chant, "Octopus, Octopus, can we cross your waters?"
C. The "Octopus" must answer: "Yes, if you (action)." Then all the students must cross exactly as the octopus says. I try to encourage them to use their creativity. Say "walk like a North Korean soldier", "dance like Psy", "crab-walk", "walk backwards", "skip", "spin in circles", etc.
D. "Octopus" runs and tags those crossing. If a student is tagged, he becomes "seaweed" and helps the octopus catch more people, but he cannot leave the spot he was tagged. He can only stretch out his arms.
E. Repeat until one remains. That one will be the next "Octopus" for the next game. (I've also played where the 1st person tagged automatically becomes the next octopus)
Hope these help!