The knit cast on is probably easiest; I taught a long time crocheter that one, english style, and she got it easily. You can show them all how to do it then spend a minute with each one. It may help if you use jumbo needles and heavier yarn so they can see it better without crowding over your shoulder.
You might want to brush up on how to do a knit stitch with the yarn in your right hand because there may be a couple of them who won't get continental, but english will be easier for them.
They can make garter stitch hand warmers - CO about 6" worth of stitches, make it long enough to wrap around the hand snugly, and seam up the ends, leaving an inch open 1" from one end. They can measure around their hands to learn about negative ease and how to measure.
sue- knitting heretic