Have the lab make 2 black & white print on matte or pearl surface paper.
Then have the students us oil paints to color with. Use Q-tips or cotton
on the end of a toothpick. You cold have them make two prints and cut
both in 1/4 inch strips pasting them down on board alternating from the
first to the second. You could also weave them, it is especially neat if
you color each first with food coloring, then weave them. Try asking the
lab if they can make a negative print of the image along with a normal.
Then weave or cut into strips and alternate the images. You may just like
the negative image (choose one that looks cool as a negative and it will
look the same when printed. You can also make negative prints with color
film, for some really different colors. Have your students shoot slide
film but have it cross processed in print film chemicals and printed like
print film, you will get some very interesting images. You will need to
go to a pro-lab for most of the processes mentioned (except the last.)
Good luck, it is tough to do really great stuff without a darkroom.
P.S. The liquid emulsion mentioned in one of these responses is called