Learn about density and volume with Full to the Rim.

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Full to the Rim

In the Full to the Rim activity, discover how many pins or pennies you can add to a full glass of water! Because of surface tension, the water will rise above the rim of the glass before it actually spills. That's because surface tension forms a kind of "skin" on the top of the water. It is also why water collects in drops.

What You'll Need:

  • Glass
  • Pan with sides
  • Water
  • Pennies
  • Sugar
  • Teaspoon
  • Straw

In this experiment, watch as the surface tension of water keeps the water from overflowing, creating surprising results. Follow the directions below and watch what happens.

Step 1: Place the glass on a pan to catch spills.

Step 2: Fill the glass with water all the way to the rim.

Step 3: Make a guess about how many pennies you can add to the full glass.

Step 4: Then test by carefully inserting a penny slightly into the water and then letting go so it gently drops into the glass.

Step 5­: Observe the top of the glass from the side so you can see the water level rising above the glass! Keep adding pennies until the water begins to overflow.

The experiment can also be performed using sugar instead of pennies.

Step 1: Fill the glass to the top with water.

Step 2: Add a teaspoon of sugar.

Step 3: Gently stir the water with a straw to dissolve the sugar.

Step 4: After the sugar is dissolved, add a second spoonful of sugar and stir.

Step 5: Then add a third, and a fourth!

Perform the sugar experiment twice, first with cold water and then with hot, and compare the results.

Go to the next page of science projects for kids: density and volume to see if it would be at all possible for you to get by on only a gallon of water a day.

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