I found this activity last summer and it was a big hit on the second day of school! Students were broken randomly into groups of four. Each group was given a stack of index cards and a challenge: Build the tallest card tower in the class! The catch? Before you could add a card to the tower, you had to write something on it that every member of the team had in common. As more cards were added, the commonalities tended to stretch a bit (we’ve all had water to drink), but it was all in the name of teamwork.