K.R.
Here's something slightly messing but interactive with the kids. Here's the items you will need:
Poster Board
Construction Paper
Stick Glue
Finger paint
1 picture of each student
Get poster board (depending on the size of the class) Each child will do a hand print on construction paper. They can do it at home (include the parents). When they return the hand print include a small picture.
Cut the hand prints out and apply the students picture in the center. Get the teacher's picture (also mounted on construction paper (maybe her favorite color) and apply in the center of the poster. Place the hand prints w/ picture around picture. You can frame it at Walmart very inexpensively. A great keepsake. Create the a flower or your own design. Don't forget to list the class names on the back and date it for years of reflection.
Good Luck.