Hey dcsma
Here's some ideas I've used:
Have them 'unzip' the form - do all of the movements on a straight line moving forward, with no 90 degree turns. Very challenging.
Have them do the moves in reverse order.
Have them do all the movements in sets of 3 to the count.
Have them do the whole pattern but replace any low block technique with something else more physical, e.g. 1 push up. Makes people think about the order of techniques, but stops them from going cold while doing so.
Have groups of 4 people start with their backs to each other to do the pattern in the shape of a cross. They should end in the same place, facing each other.
Have them perform the pattern to the count, but restart the pattern each time a new movement is reached i.e. 1, 12, 123, 1234, 12345, etc - physically demanding
Have them experiment with the speed of movements - foxtrot is one of my favourites for fun factor - slow, slow, quick quick slow
Have them balance a kidney pad on their head and then do the pattern without losing it.
Have them shout the korean names of each movement as they do the movement
Have them work out and show a self defence application for every movement in the pattern including ready stances
Have one person do the form while everybody else tries to distract them without touching them
Have them perform the whole form in slow motion, Tai Chi Style, concentrating on delivering power and last moment wrist twisting. Nip out for a bite, could take a while.
Have them sit in a side split, and perform every hand technique from every pattern that they know in order, naming them in Korean as they go. If they can't think of the next one, they repeat the last one until they remember it. 1 tech per second minimum.
Repeat the above in a low horse stance on the spot.
Repeat the above in a loose fighting stance, bouncing on the balls of the feet, techs and combinations in time with the bounce on the spot.
Have them work in teams of 4 to present a synchronised pattern display. Makes people think about timing.
Have them do the form replacing every front kick with a knee strike, every open hand technique with a closed hand technique and vice versa. Makes people think about what the techniques are rather than just going through the motions.
Have them line up at one end of the room. On command, 4 people run to the other end of the room, perform the pattern as fast as they can with no mistakes, then run back. Make it a relay. If anyone makes a mistake they run back to the start, and begin again. Good for ingraining the movements in the memory early on in the learning process, without worrying about perfection.
Have fun
Gnarlie