Congratulations! You're probably already doing flower dissections with your students, but I find ditch daylilies great for that! At the science center where I work, for most of the year we dissect alstroemeria (inexpensive and readily available year-round), but in season I prefer large cup daffodils (like 'Ice Follies' or daffs left over after a daffodil show) or ditch daylilies. We dissect the flower, stem and leaf and look at the parts under microscopes. Daylilies left over from a show would also be great. With the show daffs, most people write the name of the flower on the stem with a ballpoint pen and the diversity of the flowers plus their names add interest to the activity.