Draw what I say is a cooperative learning activity and it works well when you are trying to get students to learn or recap models and diagrams. I have used it in Busines Studies and Economics, but it should work well in Geography, Science and DT.
You just need to get pairs of students to work opposite each other with some kind of barrier between them (folders work well, but anything that prevents them from seeing each others work is the important thing). Student A is then given a model that they have to describe to student B and student B has to try and draw it based on student A's verbal instructions. While it sounds simple it does get the students engaging in and thinking about the content. There is also a variation on this activitiy called Make what I say but I have not thought of a way of using this yet!