Purchase a postcard for each member of your class (or just make some and photocopy or get a stack of free ones available at some stores. You could use this one or see all our templates.). Each student writes his or her name in the name and address space.
Turn them picture side up on a table, have each student choose one (without looking at the name), then he or she will write a message to the person whose name is on the other side. If a student chooses the postcard that has his or her own name on it, the student must choose again.
Give the students a certain amount of time to finish. For lower-level students put a cloze on the board to help them. Much like this.
Greetings from _________! I am sitting ______________ drinking __________. It is ____________. The weather here is ____________. Today I went to ___________________ and tomorrow I’m going to ______________. I’ll be home __________________. See you soon.