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Sandy Structures
 To build a great sandcastle you need sand and water, but how much water is enough? And how much is too much? Try this activity to discover how much water is just right.
What You Need
Bucket
Small plastic container
Dry sand
Water
Large wooden spoon or a small hand shovel
Large plastic container
Small stones or marbles
What to Do
1. Using the small container as a measure, add 3 containers of sand and 1 container of water to the bucket.
2. Mix the sand and water well with a spoon or shovel.
3. Fill the small container with the sand and water mixture. Pack the sand well. Turn the container over to make a small tower.
4. Place the large plastic container on top of your tower. Add stones or marbles until the tower cracks or collapses. How many stones or marbles did you add?
5. Repeat steps 1 to 4 two more times using these mixtures:
8 containers of sand and 1 container of water
12 containers of sand and 1 container of water
Which tower held the most stones or marbles?
How it Works
Recently, scientists found out that the best mixture for sand structures is one part water to eight parts sand. (Your results might have been different though. The strength of your tower depends on the size and shape of the sand grains and the dryness of the sand.) Just the right amount of water forms tiny bridges between the grains of sand.
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