Actually, spider plants are some of the easiest plants to grow. You chose good for the age group. Print up instructions for them (and parents).
Bright light in a window is good. Turn them every few days. Keep evenly moist if possible but they will take a little neglect. But not flooded either.
Are you putting drain holes in those paper cups? They will need a saucer or something under them. When the cups start to split or disintegrate they will need to move those plants to something sturdier with drainage. A margarine tub or a real pot maybe.
And baby spider plants come off the mother plant with roots already started so you don't need to wait for longer water roots to form. Just make sure the root 'nubs' have contact with the potting soil.
Mine grow outside here. I have a row of them in hanging pots along the eaves of my porch. I have to '
weed' out babies that fall off onto the ground and take root there where I don't want them.
In my husband's high school agriculture department we used to host preschoolers all of the time and take cuttings for them to plant and take home. I wonder how many of those 'took'? We supplied, plastic cups, potting soil, tongue depressors and plastic bags and a rubberband so each plant went home in a mini
green house. It was fun.