MnSTEP Teaching Activity Collection > MnSTEP Activities > Osmosis Eggs

Osmosis Eggs

Karen Weisbrich
Rocori High School
Cold Spring, MN 56320
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The purpose of this activity is to have students observe the process of osmosis using an egg. The students will also be using the steps of the scientific method to write a formal lab report.

Learning Goals

  1. The students will understand the process of osmosis by observing water enter and leave an egg.
  2. The students will develop an understanding of the vocabulary terms used in the process of osmosis.
  3. The students will practice the skill of writing a formal lab report.
  4. The students will be using the scientific method as they complete this activity.

  • osmosis
  • isotonic
  • hypotonic
  • hypertonic
  • osmotic pressure
  • selectively permeable membrane
  • qualitative data and quantitative data

Context for Use

This lab activity can be used in 10th grade biology. It will take about 4 to 5 days to complete. The students will need an egg, a container to hold the egg, a balance to mass the egg, and 1 cup of the following liquids: vinegar, syrup (corn syrup works best). I use this activity while we are covering the concepts dealing with the cell membrane. Students work with lab partners to complete this activity.

Subject: Biology:Cell Biology:Cell Processes:Membrane Transport
Resource Type: Activities:Lab Activity
Grade Level: High School (9-12)

Description and Teaching Materials

The students will use the steps of the scientific method to write up a formal lab report on the process of osmosis.
  1. The students mass their egg and make observations.
  2. The students put their egg in 1 cup of vinegar for 2-3 days to dissolve the shell.
  3. The students remove the egg from the vinegar and rinse off the excess egg shell.
  4. The students mass their egg and make observations.
  5. The students put their egg in 1 cup of syrup overnight.
  6. The next day the students mass the egg and make observations.
  7. The students put the egg in 1 cup of water overnight.
  8. The next day the students mass the egg and make observations.
  9. The students hold their egg over the sink and stick it with a pin to observe osmotic pressure.

The students are required to make a hypothesis each day before they put their egg in the different solutions. The students record the masses and observations each day and construct a data table. They are also required to make a bar graph of the masses in each of the solutions. At the end they form a conclusion about what was happening to their egg by using the vocabulary term listed in the goal section of this lesson.

Teaching Notes and Tips

I have the students work with lab partners to complete the lab, but each student is responsible for writing up their own lab report. This year to make this activity more inquiry based after they have done the initial activity, I am going to have the students bring in different solutions from home and have them predict what will happen to the egg if it is placed in the various solutions. After they predict what will happen I will have them experiment with the solutions. This part will be added to their lab report. I may make it a contest to see who can come up with a solution that is the most isotonic to the egg.


I assess this activity by grading their lab report making sure it has all the parts of a formal lab write-up.


9-12. IV. A.3 Cell Membranes
9-12. I. B. 1-4 Scientific Inquiry

References and Resources