Key factors for engagement:
- Something that will unashamedly hook in these children (often boys) from the start: an urgent rescue, mysterious footprints, an office burglary, etc.
- Opportunities for frequent activity i.e. making, moving, discussing, rather than just listening. Your choice of enterprise can influence this enormously.
- Careful use of drama conventions which stop the children from feeling self-conscious and, hence, resorting to silliness to protect themselves.
- The teacher modelling that children's ideas will always be accepted and can really influence the direction of the work - the teacher using "yes, and...." instead of "yes, but...".

As for ensuring that everyone comes along for the ride, be prepared for some children to take to it slower than others, after all it does look and feel very difficult from 'normal' school work.