I did this easy printmaking lesson with first graders, but I think even kindergarten students could handle it at this time of the school year.
The materials are simple: chip board or cardboard cut into small squares, thick string, Elmer's glue. printing inks (I used secondary colors), brayers, barrens, and white paper.
Step 2 (optional): Seal the strings down with a coat of acrylic paint. If you have the students do this it will take another day to dry, so you may choose to do this between sessions.
Step 3: With the glue (and paint) now dry the prepared plates are ready for printing. I usually set up a little printing station with three colors at it. I make sure I squeeze out the ink, but let the students practice rolling the brayers. Before students come up to use the ink have them write their names on white papers. Remind them that clean prints don't have fingerprints so they need to be really careful handling the paper while using the inks. For this particular project the students rotated around the printing station overlapping the three colors and turning their printing plate one turn with each new color to get three prints that overlap each other.
*while groups of three are printing have a small activity available for those waiting at seats.
Step 4: Display or mounting. For this project I had ended up cutting circles out of the prints, and stringing them to make a sort of curtain. They were backed with sticky gold paper which held them on the fishing line. Displayed near a vent in front of a window the individual circles would spin and catch the light.