For each group:

• 4" by 4" square piece of fine wire screening
• twist tie (such as a garbage bag tie or plant/landscaping wire) for tying screens
• clear glass jelly jar (~1/2 pint) or coffee can
• 3-5 cups of playground sand (amount depends on the exact size of the jar/can)
• aluminum pie pan
• medicine dropper
• food coloring
• pencil
• cup of water