Investigating Osmosis using water and gummy bears

Katie Melgaard, New Heights School, Stillwater, MN based on "Observing Osmosis", author unknown.
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In this biology classroom lab, students investigate the affect of soaking a Gummy Bear in water. They collect measurements of height, width, and mass before and after the soaking of the candy overnight. Students calculate % change for each factor and graph the data on a bar graph. They then develop a new, testable question and follow through with the new experiment. A copy of the instructions and rubric is provided.

Learning Goals

1. This activity is designed for students to investigate osmosis.
2. The students will calculate the percent change of height, width, and mass, graph the results, and analyze the results.
3. The students will develop an experiment and implement it.

Key Concepts
1. Science is a process that continually finds more questions to ask.
2. Osmosis is the transfer of water to equalize two sides of a barrier.
3. Selectively permeable membranes allow some molecules to move through, while not allowing others.

Vocabulary Words:
-Selectively permeable
-Active and passive transport
(isotonic, hypertonic,hypotonic--easily would fit too)

Context for Use

This is a simple lab that could be done in middle levels or high school. This would take about a half hour, one hour, and another half hour--spread out over 3 days. This lab is nice because all that is needed is Gummy bears, containers for water, and a way to measure the mass of the bears. The activity is a great intro lab into the concept of osmosis and diffusion. It would easily adapt into other settings by adapting how much student involvement there is in the setting up of the experiment.

Description and Teaching Materials

Start with discussing the main question with the students: "What effect, if any does soaking Gummy Bear candies in water have on the size of the candy"?
Students will record their predictions and work in groups to design a data collection table for their expected data.
The procedure of the lab is structured and given to the students. Materials needed: Gummy bears (at least 2 per group), method of measuring height and mass of bear, containers for water. Bears will soak in water overnight, then students will record second set of measurements, calculate % changes, and graph percent changes. Then they will be given definitions of the vocabulary words and asked questions analyzing their results. The students will then develop questions they now have and develop a new experiment based on the new questions. After they have completed their second experiment, they will discuss first in small groups and then as a class their results.

I modified this lab to be more inquiry based from a lab I received at a lesson swap at one of the recent MN Biology Teachers Conference at the Science Museum; I don't have any information about the author of the lesson.

See attached Observing Osmosis handout and rubric. Assignment handout and rubric (Microsoft Word 147kB Sep4 08)

Teaching Notes and Tips

This is meant to be a pretty structured inquiry lesson to help students get used to having a little more say in their experiment design and organizing their data.

*For high school students, or higher achieving students, it would be easy to include the terms hypertonic, isotonic, and hypotonic and have them determine what types of substances would fit under each term.

*It would be good to remind the students to be careful with their gummy bears on the second day because the bears will probably be fragile.


Students will record their prediction, data, calculations, graphs, and analysis in their notebooks. Copy of the rubric is attached.


9-12 I.B.3 Applying math to analyze data
9-12 IV.A.3 Cell membrane as a selective barrier

References and Resources