Materials
Plaster of paris
Water (1 L)
Quart-size zip-closure plastic bags, one per child
Paint or food coloring
Instructions
What to do
1. Place 1/2 cup (125 mL) plaster of paris in each zip-closure bag and add the appropriate measure
of water. Squeeze out the excess air and close the bags securely.
2. Ask the children to mix the powder and water by squeezing the bag.
3. When they are finished, have the children choose two colors. Help them unzip their bag, add
the paint or food coloring, then close the bag again.
4. Ask the children to squeeze the bag again to mix the colors and continue squeezing until they
have achieved the desired mix of color. A marbleized effect is achieved with less mixing.
5. Once the mixture begins to harden, have the children stop and set their bags aside. Open the
bags slightly if you want them to dry more quickly.
6. Once the plaster has set, remove the bag.
More to do
More art: Place small decorative objects in the plaster mixture before it sets.
Science: Have a discussion about the changes that occurred when the materials were mixed
together. Produce simple chemical reactions for the children to help them understand.
