Sweat It Out

This activity is modified and used with the permission of the AIMS Education Foundation. Find it in the AIMS Publication, Jaw Breakers and Heart Thumpers.

Liquid water is critical to the survival of most living things. In some organisms, up to 90% of their body mass comes from water. Many fruits and vegetables are more than 75% water.

To analyze and compare a variety of fruits and vegetables based upon the mass of water in these foods

For each student:

Data Collection Chart -- (design this chart as a class prior to the activity)

For each group:

Balance
wax paper
paper plates
a variety of fruits and vegetables

For the teacher:

potato peeler and/or sharp knife

Part One

As a group, discuss the fruits and vegetables you'd like to use for this experiment.


Ask students to bring in the foods.


Begin this experiment on a Monday or Tuesday so that students may make at least daily observations.

Part Two

1. Discuss setting constants for this experiment. As a group, decide whether you're going to peel each fruit and vegetable. Cut slices from each fruit and vegetable for your test samples.
   
2. Before beginning the experiment, predict which foods will lose the most mass due to water loss.
   
3. Demonstrate how to use the balance to measure the mass of the wax paper and paper plate. Place the wax paper on the paper plate so the paper plate doesn't absorb water from the sample.
   
4. Record the mass of the wax paper and paper plate. The mass will be a constant.
   
5. Give each group several slices of a food sample to observe and measure.
   
6. Students should record these observations in the data collection chart.
   
7. For at least four days, students will make daily observations of the food sample. They will not only describe any changes to the sample but will measure the sample daily.
   
8. Calculate daily changes in the mass of the food samples.
   
9. Graph these results.
   

1. What did you and your classmates do to keep the testing conditions the same? (Controlling variables)
   
2. Why is it important to keep testing conditions the same way?
   
3. How did the mass of the foods change? What caused these changes?
   
4. Organize the foods that were tested to show those that lost less water compared to those that lost the most water. Based upon this list, predict what other foods might lose as much mass.
   
5. Since human beings have a high percentage of water in their bodies, how do we replace water that is lost through sweating?
   

1. Calculate the average loss of water for each food.
   
2. What foods should lose the least amount of water? Create an experiment to test water loss.
   
3. Find out about food the astronauts eat in space.
   
4. Explore the effect of temperature on the mass loss of fruits and vegetables.