It is important here to create a story so the roles have significance to the students. The story may be around a construction site where the students have to prepare themselves for their jobs. The builders can pretend to put on the safety helmet, safety vest, steel capped boots and tool belt. The bulldozers can do the same with keys, or they can be the actual bulldozers with sound and actions.

We are going to do some very important jobs today. We will have half of you as builders the others as bulldozers. It will be your very important job to attempt to either build or knock down the building in our construction site.

Builders, using your left hands you must build the 'building' (cones) before the bulldozers knock them down.

Bulldozers, your job is to knock them (cones) down using your left hands, before all the builders can build them.