One of our small group activities is to look at mitosis in onion cells. Anna Clarke, recommended the University of Arizona site which has an Online Onion Root Tips activity for those without access to the slides or microscope. It also provides a good review even if you do have those resources. Dr. Paul’s page on onion cell division is a good supplement to the Arizona site because of its great cell images.
If you’re feeling ambitious and want students to make their own slides, you can try the SAPS page on Mitosis in root tips.