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How Much Water Is in a Fruit?

Author(s): Nancy P. Moreno, PhD, Barbara Z. Tharp, MS, and Judith Dresden, MS.


Students may want to compare the weights of different dried and non-dried food items. Some possible examples are listed below.

  • Raisins and grapes 
  • Dehydrated potato slices (from potato mixes) and fresh potato slices 
  • Banana chips and fresh banana slices 
  • Beef jerky and strips of raw beef 
  • Dried peas and fresh peas 

Approximately 7/10, or 70% of the human body consists of water. Have students use the following formula to calculate approximately how much of their own weight is water.

Your weight x 7 =_______.

Your answer from step 1 ÷ 10 = amount of water in your body.

Students also can follow the steps below to calculate the percentage of their bodies comprised of water. 

  1. Count out the number of snap-together math cubes equal to your weight (i.e., 45 lb = 45 cubes).
  2. Separate the cubes into 10 equal groups 
  3. Place 7 groups in one set and 3 in another set. 
  4. The largest set represents the portion of your body that is water. 

Have students use the values derived from their calculations to estimate the volume of water in their bodies (1 pound of water represents approximately 2 cups). 

Ask students, Which of these measures is used most commonly for liquids? Why do you think this is so? Can you think of a way to convert a measure of volume to a measure of weight, or vice versa?

Funded by the following grant(s)

National Institute of Environmental Health Sciences, NIH

National Institute of Environmental Health Sciences, NIH

The Environment as a Context for Opportunities in Schools
Grant Numbers: 5R25ES010698, R25ES06932

Houston Endowment Inc.

Houston Endowment Inc.

Foundations for the Future: Capitalizing on Technology to Promote Equity, Access and Quality in Elementary Science Education