Two hours fly by so it really depends if this is the first in a series or a one time class. Which actually could turn into future private lessons.
I would bring a few cookies. Some pre flooded others plain, sprinkles, some icing transfers , some swatches of icing sheets , and maybe even some ready made sugarveil. ( the needlepoint design could help here)
You can do simple flooding with wet on wet designs, show them a simple border , use the sprinkles appropriate with the design etc.
With the preflooded cookies ,stenciling, stamping or gluing transfers and adding borders are all quick and easy. Here using the needlepoint sugarveil can work.
Have fun and good luck.