What you needPaper
Take your acrylic paint and water it down slightly then pour into a water spray bottle.
Place the child’s hand against the paper and spray over the hand. Traditionally this paint was held in the mouth and sprayed over the hand from the mouth. If you intend on having your kids do that make sure you use non toxic paint.
For a safer method, use food coloring, the overall color will be lighter but it will be a more “traditional” attempt to re-create the art.
You can use the same acrylic water paints in a spray bottle and paint the classroom windows using the same hand method.
Then when the theme is complete the cleaner can use a scrubber to remove the paint from the windows.