How about a team game or two? I like to have everyone stab each other. If you don't have enough rubber knives, cut up an old garden hose into ten inch lengths. Give half the class a 'knife' and tell them to stab the other half. Then change over. Then play gangs, have two onto one, three onto one, then have the defender able to use another person as a shield and keep the pace up. If 'knives' are inappropriate, use feathers, bananas or anything that won't upset the timid. Use music to pump them along.
In five minutes of frantic fun they warm up, have a laugh, relax and 'cohese' a little as a class. You can then make teaching points by asking how people felt about the exercise? Did they think it was easy to avoid the slashes and stabs? How about the multiple attacker scenarios? What about using the human shield? and so on.
They are now switched on, thinking self defence not fitness and yet are warmed and pumped, ready to proceed.
The problem I see is the program will have them getting warmed up then...? Listen to a lecture, watch a demo then practise? ( As in:explain:demonstrate:practise Like this, do that.. go on)There is the risk of a drop in energy as the pace changes. So why not roll right into the Hock's Block as the 'warm up'. Say you are going to warm them up with a practical technique, then have them speed up gradually.
Good luck,
Redcap