Believe it or not, this activity uses diapers to help students observe physical change.
- Graduated cylinders
- Distilled water
- Measuring tape
- Large Ziploc bags
- Other supplies may be
needed depending on
the direction that
- Investigation Write-up handout (pdf)
- Kitchen Chemistry: Science Experiments to Do at Home, by Robert
Gardner and Jane Steltenpohl; ISBN 0671677764
- Sciencesaurus: A student handbook, (Great Source Education Group);
- States of Matter Files: Transform!, (Discovery Communications,
copyright 2000, http://school.discovery.com/); Student Resource
Guide Item #739581, Teacher Resource Guide Item #742452
- Teacher Resource Book 3, State Science Core Teacher Text Grade
Five, "What's the Matter?" Student Literacy section 8.1.1 to 8.1.4,
available from Jordan School District
Background for Teachers
Diapers contain fluffy filler that absorbs some liquid, but a white
crystal mixed with the filler does most of the job. That crystal is sodium
polyacrylate, a product developed for use in astronaut diapers. It is now
used not only in baby diapers and a variety of personal products, but in
gardening as well. Potting soil containing these water-holding crystals
can is available at many garden centers. It is also marketed as something
to be injected under lawns in our drought-prone state in order to conserve
A physical change is seen as the crystals absorb water. They expand
to many times their original size. If left to dry out over a period of time,
they decrease in size. Because the crystals swell in water it is not be a
good idea to rinse them down the sink.
Warning: Caution students not to rub their eyes, noses, or face while
working on this activity. Sodium polyacrylate has the same effect
on body fluids and may be harmful to the students.
Intended Learning Outcomes
1. Use Science Process and Thinking Skills
2. Manifest Scientific Attitudes and Interests
4. Communicate Effectively Using Science Language and Reasoning
6. Understand the Nature of Science
Invitation to Learn
As a class, list the physical properties of diapers in a group
discussion. Physical properties may include size, shape, color, odor, or
- Discuss any chemical properties from the Invitation to Learn.
The diaper cover will burn or melt. Filler will burn or melt.
- Separate the components of the diaper. One of the best ways to
separate the crystal is to pull all the filler out of the diaper, put it
in a Ziploc bag, seal it, and shake it. The crystals will separate
from the filler and gather in the corner of the bag.
- Discover the white crystals in the filler. What are these crystals?
What is their function in the diaper? (absorb liquid)
- Start to form questions to be used for class, group, or individual
investigations. Questions may include, but are not limited to:
- How much water will one diaper absorb without leaking?
- What is the ratio of weight of water absorbed to the weight of
the crystals? (good math connection)
- Does the temperature of the water affect how quickly the
water will be absorbed?
- Do more expensive diapers contain more crystal? Will more
expensive diapers absorb more water?
- Do different sizes of diapers contain different amounts of
- How much more water will a regular diaper hold than a swim
- How long does it take for the waterlogged crystals to dry out?
- Design an investigation as a class, group, pairs, or individuals.
- Write question, hypothesis, materials, and method before
- Distribute materials to each group according to what they’ve
listed on the Investigation Write-up handout.
Show students a baking soda and vinegar reaction. One of the most
common ways this is done is with a bottle or test tube containing a small
amount of vinegar and a balloon containing baking soda stretched over
the bottle opening. When the balloon is tipped up and the baking soda
mixes with the vinegar, a gas is formed that plumps up the balloon.
Students design investigations based on this idea. Questions may
- How does the temperature of the vinegar affect the amount of gas
- Does the amount of vinegar used affect the amount of gas
- How does the type of vinegar affect the amount of gas produced?
- How does the test tube size affect the size of the blown-up
- How does the number of times the balloon is stretched affect how
big it gets?
- Use the wet crystals as a medium for growing a plant. No dirt is
needed. Water it every couple of days and include a small amount
- Place students of different abilities in each group. Each student
should have a meaningful role.
- Science Fair Experiments follow this basic idea. A question is
formed and investigated, and then data is gathered and analyzed.
- Investigate dishwashing liquid. How long will the bubbles last?
Do they last longer if you start with cold water or hot water?
- Assess the completed Investigation Write-up.
- Ask students to write about what they learned.
- Have students design an investigation on another topic.
- Ask students to list evidence that the crystals change was a
- Give each group the opportunity to present their findings to the