You must make enough pairs of pictures for each learner to have one picture. For example, if you have 20 students you must have ten pairs of pictures. (The pictures can be very simple and very small! You can easily get ten small drawings on one sheet of A4 paper which you then photocopy to get a pair. If the drawings are all similar, it will be more difficult and produce more discussion! Cut the sheets of paper up and you will have 20 drawings.)
Give each learner one picture. Each learner must then find which other learner has the same picture. The level of difficulty of language is determined by the drawing you choose to do.