Divide the students into two equal teams.
Have teams face each other across from an imaginary line. You could use a rope divider if you like.
Assign one side to be “Crows” and the other to be “Cranes.”
The leader stands at the end of the group in the centre so all players can see and hear him/her. The leader calls out either “Crows” or “Cranes.”
If “Crows” are called, the Cranes must turn and run a short distance to their “base” before the Crows tag them. If any Cranes are tagged, they become Crows, and head to the other side for another round. The same applies when “Cranes” are called.
Play until everyone is on one side.