Each group needs:

• water, 2 gallons (7.6 liters)
• 1 large waterproof bin, to catch any spilled water
• 4 small disposable plastic containers (available at grocery stores, or cut bottoms off milk jugs/ juice cartons, or use very thin Tupperware containers from a thrift store)
• scissors and/or hacksaw, for cutting plastic containers
• Four Types of Dams Worksheet, one per person

Embankment dam materials for each group:

• course sand, 1 cup (play sand works, but tube sand or sand for concrete works best)
• plastic wrap, 1 x 12 in (2.5 x 30 cm) strip, for waterproofing; foil or paper also work
• 1 tsp (5 ml) modeling clay, for the spillway

Gravity dam materials for each group:

• 10-15 small dominoes, wood or metal blocks (blocks should be close to domino size)
• 1 tsp (5 ml) modeling clay, for the spillway, to secure blocks, and as grout between blocks; can substitute tape and plastic wrap for clay

Arch dam materials for each group:

• modeling clay, one large handful

Buttress dam materials for each group:

• modeling clay, half a handful
• 5 small (1-3 in, or 2.5-7.6 cm) dowel pieces (or straws or popsicle sticks), for dam support