Is your next unit on descriptions of people? Try this fun and challenging activity with your ESL students (pre-intermediate and above).
The game is basically as follows.
Break your class up into teams of 4 or 5 (each team must have at least 2 cellphones and 2 cameras). The teams then go to the street and split up so that one half of the team is at one end of the block, and the other half is at the other end. 
They (for simplicity, we will say team 1, blue squad) then must call the other members of their team (team 1, red squad). Red squad team 1 begins the game by taking a picture of and describing a pedestrian (stranger) who is walking down the block toward blue squad. Based on Red Squad’s description of the pedestrian, Blue squad must identify and photograph the same individual.
For every correctly identified and photographed individual (pictures by red and blue squads must indeed be of the same person), team 1 is awarded a point. Teams 1, 2 and 3 compete against each other for 45 minutes (and everyone must have a chance to describe individuals), and team with the most points at the end of the time wins.
If that sounds confusing, here’s a comically poor diagram, illustrating the concept. If it’s still confusing, modify it to however makes most sense to you. Done correctly, this activity makes your students feel like secret agents.