WATER IS THE DIFFERENCE!
Authored by: IPS instructors: Phyllis Bryant, Stacey Mitchell, Tanisha Williams
Ball State University Pie Scientist; Cheryl Kellogg
Summary:
 Students will trace their bodies and color portions to represent the amount of
water in their bodies. They will make comparisons of their body water content to
the water content of grapes/raisins, plums/prunes, and other hydrated/dehydrated
items.
Purpose: the student will be able to …
 Explain that about 2/3 or 67% of the mass of a cell is accounted for by water.
 Demonstrate that water is the main ingredient of living organisms
Standards Addressed: (Indiana State Standards)
 6.1.2 Give examples of different ways scientist investigate natural phenomena
and identify processes all scientists use, such as relevant evidence, the use of
logical reasoning and the application of imagination in devising hypotheses and
explanations, in order to make sense of the evidence.
 6.1.3 Recognize and explain that hypotheses are valuable, even if they turn out
not to be true, if they lead to fruitful investigations.
 6.4.7 Explain that about 2/3 or 67% of the mass of a cell is accounted for by
water. Understand that water gives cells many of their properties.
 6.5.7 Explain the strength and weaknesses of using an analogy to help describe
an event object, etc.
Materials:
 Dried fruit, ripe fruit, small house plant, dried house plant,
 Balance, bathroom scale
 Butcher paper or 2-3 newspaper sheets taped together for each student
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 Crayons, scissors
 Gallon jugs or 2 liter containers (you will need 12-15 gallon jugs per
demonstration)
 4x6 index cards (enough for each student)
 Tape
 Several pictures of plants and animals (with their weight listed on the back)
 Dehydrator, simple solar oven or window sill
Making Connections:
People drink water everyday but they rarely think about the proportion of their bodies
that is composed of water.
Learning how much water is contained in living organisms encourages students to
appreciate life’s dependence on water.
Background:
Active, living organisms are composed of at least 50% water. This is true whether
they live in a desert, (some cacti can be nearly 90% water) or in the ocean (whales are
75% water).
Within single cells, water content ranges between 67 and 85 % percent. Water in the
entire body by weight, of course varies with age, sex and physical conditioning. The
heart and lungs contain the most water, about 80%. Fat contains about 20% and bone
is the lowest at around 43%.
Fat increases with age while muscle mass decreases, so in old age the body may
contain only 45% water. Infants, by contrast will average 73% or more.
Water is in a number of different compartments in the body. Given a total of 42 L
(11gal) found in the body; 28 L (7.4 gal) are inside the cell, the remaining 14 L (3.7
gal) are outside the cell: from that 14 L, 3(0.8 gal) are in the blood and 11 L (2.9 gal)
are in the spaces between the cells.
After oxygen, water is the body’s most important nutrient. It has an important role in
nearly every major function, such as regulating temperature, carrying nutrients and
oxygen to the cells, removing waste, cushioning joints, and protecting organs and
tissues.
Procedure: (warm-up)
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Ask students if they think we have water in our body.
Ask students to guess the percentage of their body that is made up of water.
All living cells are at least 2/3 or 67% water, many organisms are more.
Tell them that the human body is approximately 70% water (actual
amount varies with gender and age)
 Ask them what 70% water would look like.
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Activity I:
1. Have students work with partners to trace their body shapes onto butcher paper or
newsprint.
2. Explain that the percentage of water in their bodies is approximately 70 %
3. Have students color 70% of the figures they have traced onto the paper. (You may
want to have students fold their drawing into 10 equal parts and color 7 of the 10.
4. Have students weigh themselves. (i.e. 100 lb)
5. Students can calculate the amount of water in their own bodies.
6. Student weight multiplied by 70 % as a decimal. I.e. 100 lbs x .70 = 70 lbs of
water.
7. Ask students to make a hypothesis (testable statement) of how many gallons of
water they contain.
8. Ask students to devise a way to test their hypothesis.
9. Have available gallon jugs, filled with water.
10. Students should come up with an idea to weigh the water (8 lbs) and then use the
calculation; student weight x 1 gal/8lbs or with our 100 lb student; 100 lb x
1gal/8lb=12.5 gal of water.
Activity II:
1. Ask students the difference between several groups of foods: raisin/grape
hydrated and dehydrated banana, dried tomato and fresh.
2. Have several pairs of de/hydrated specimens available to students and have them
choose one.
3. Ask students to give a hypothesis regarding water content in their food choice.
4. Ask students to devise a way to test their hypothesis.
5. Students can weigh dry foods and wet foods and calculate the difference between
them.
6. Direct students to compare the wet mass to the dry mass by subtracting the dry
mass from the wet.
7. Ask students how much of the mass of your plant is accounted for by water.
8. Have students explain the statement that approximately 2/3 of the mass of each
cell is accounted for by water.
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Activity III:
1. In groups of 2, have students collect several items to dehydrate. You may have
prearranged items for this purpose, or the students may come up with their own
ideas.
2. Have students take the mass of their item and then place it in a dryer you have
selected for this purpose. This could be a dehydrator, oven set at low temperature
or window sill.
3. Once dehydration has occurred, (this may take several days) have students take
the mass of their item again.
4. What do they expect to see? Discussion
5. Is the mass of the cell at least 2/3 water? Discussion
Activity IV:
1.
2.
3.
4.
Students may wish to make a simple bar graph demonstrating % water to species.
This could be done with % water on y axis and species on the x axis.
This could be done as a class project or group project.
If this is a group project, students could present their evidence to the class that at
least 2/3 of the mass of the cell is made up of water.
Assessment:
1. Have available several pictures of plants and animals with their mass recorded on
the back and assign one to each student.
2. Have available a reference chart showing body water content of students’
organism.
3. On a 4 x 6 index card, have the students draw the outline of their plant or animal.
4. Estimate their plant or animals water content by coloring the corresponding
portion on their outline.
5. Have students calculate the exact amount of water for their organism using the
mass on their picture and the percent water content from the reference chart.
6. Discuss that at least 2/3 or 67% of the mass of an organism is made up of water.
Extensions:
 Obtain a food drier or build a solar oven, (see attached instructions) and have
students dehydrate several food items.
 Students may illustrate organs on their cutout figure and research the water
content of each organ.
 Other water topics might be:
 Food groups and organic molecules
 Diffusion and Osmosis in the Human Body
 Water, Characteristics and Processes
 Have several books available from your library about water. Students may be
encouraged to devise their own research.
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Teachers Notes:
1. Grade Level: 6th (accommodations may be made for special needs) can be adapted
for higher grades
2. Subject areas: Life Science, Health, Language Arts, and Math.
3. Duration: Activity times should be around 45 – 50 minutes.
4. Skills: Organizing information, estimating, calculating, categorizing. Analyzing,
comparing and identifying patterns
5. This unit could be used comprehensively with some accompanying math and
language arts handouts
Resources:
 Berga, Gilda. 1989. The Human Body. New York,N.Y.: Doubleday
 Burnie, David. 1989. Plant. New York N.Y.; Alfred A. Knopf
 This lesson was adapted from Aqua Bodies; from the Project WET
Curriculum & Activity Guide produced by the Council for Environmental
Education and the Watercourse at Montana State University.
 Special Thanks to:
 Phyllis Bryant of John Marshall School, Indianapolis IN. for The Language
Arts Page
 Stacey Mitchell of John Marshall School, Indianapolis IN. for
Accommodations
 Tanisha Williams of John Marshall School, Indianapolis IN. for Math Helps
 And to Mackenzie Williams for keeping us on task and making us laugh.
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PIZZA BOX SOLAR OVEN
Here is a simple solar oven that will help you dehydrate your own items.
Materials:
 One large pizza box
 Newspapers (5-6 sheets should be fine)
 Tape
 Scissors
 Black construction paper
 Clear plastic wrap
 Aluminum foil
 A piece of notebook paper
 A pencil or pen
 A ruler or wooden dowel
Construction:
1.
Make sure the cardboard is folded into its box shape and closed
2.
Place the piece of notebook paper in the center of the lid of the box and
trace its outline on the lid. Put the piece of paper aside.
3.
Carefully cut the 2 long edges and one of short edges of the rectangle that
you just traced on the lid of the box, forming a flap of cardboard.
4.
Gently fold the flap back along the uncut edge to form a crease.
5.
Wrap the underside (inside) face of this flap with aluminum foil. Tape it
on the other side so that the foil will hold firmly. Try to keep the tape from
showing on the foil side of the flap. The foil will help to reflect the
sunlight into the box.
6.
Open the box and place a piece of black construction paper in so it fits the
bottom of the box. This will help absorb the suns heat.
7.
Close the box; roll up some newspaper and fit it around the inside edges of
the box. This is the insulation that helps to hold in the sun’s heat. It should
be 1 to 1.5 inches thick. Use tape to hold the newspaper in place, but only
tape it to the bottom of the box, not the lid.
8.
Cut 2 pieces of plastic wrap an inch larger than the flap opening on the
box top. Open the box again and tape one piece of plastic to the underside
of the flap opening. After taping one side, BE SURE TO PULL THE
PLASTIC WRAP TIGHT, and tape the other piece of plastic wrap to the
top of the lap opening. Again, be sure the plastic wrap is tight and tape
down all four edges to form a seal. This creates a layer of air as insulation
that will help to keep the sun’s heat in the box.
Operation:
1. On a sunny day, choose your items to dehydrate.
2. If it is cold outside, put a towel under your oven
3. Open the flap and turn the box so the foil is facing the sun.
4. Move the flap up and down and note how the sun is reflected
5. Use a stick to prop up the flap so that the sunlight bounces into the box
6. It will take at least a half hour to warm up.
References: from the US dept of Energy’s Office of Energy Efficiency and Renewable Energy.
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