Painted Cardboard Tube Heart Numbers Materials needed: Cardboard tubes (one tube for each student), clothespins, tempera paint, paint smocks or t-shirts to protect clothing, scissors, paintbrushes and trays, construction paper, markers, tape or poster putty, and counters (we used Valentine's M & M's in the picture.) Have the children paint the cardboard tubes with any color desired (our … [Read more...] about Valentine’s Math and Science Activities for Preschool!