First, pair up the children and sit them down with their legs flat (on the carpet) and spread out. Now give the pairs numbers 1,2,3, and so on.
You call a number, and that pair will jump up and run around the whole of their team and sit down. The first one to sit back in place is the winner. Or, as a team, the first pair runs around and as soon as they are in place, the next person gets up and runs until the whole team has run around the whole team.
The first team to all sit down is the winning team.