Have two different copies of a picture. Label one picture as correct and one as incorrect. Arrange the students in pairs and give one student the correct version and the other the incorrect version. The students must talk about the pictures without showing each other their copies. They discuss and write down the differences. The differences, for example, can be missing or extra objects, or different positioning of objects (e.g. in one picture a box is on a table, in the other it is under the table).