Introduction to Osmosis

This activity begins with a student investigation of the phenomenon of osmosis and then moves to analysis of the mechanism and implications of osmosis. In Part I, "What is happening to these eggs?" students observe and analyze the effects of osmosis on eggs. In Part II, "Understanding Osmosis", analysis and discussion questions introduce students to the molecular basis for osmosis and challenge students to apply their understanding of osmosis to several real-world phenomena.

Download Student Handout: PDF format or Word format

Download Teacher Preparation Notes: PDF format or Word format

The Teacher Preparation Notes provide instructional suggestions and background information and explain how this activity is aligned with the Next Generation Science Standards.

We invite comments on this Hands-On Activity and the accompanying Teacher Preparation Notes, including suggestions for other teachers who are planning to use the activity, useful preparatory or follow-up activities, additional resources or any questions you have related to the activity, or a brief description of any problem you might have encountered. If you would prefer to send your comments or questions in a private message, please write Ingrid Waldron at

See also a complete list of activities:
Hands-on Activities for Teaching Biology to High School and Middle School Students



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2014 revisions

The experiment with dialysis tubing has been replaced by a demonstration of osmosis in eggs. A version of the dialysis tubing experiment is available in "Diffusion across a Selectively Permeable Membrane" ( Most of the questions in the Student Handout have been revised for greater clarity or interest.

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2013 revision

The questions in the Student Handout have been clarified and improved to enhance student understanding. The Teacher Preparation Notes have been updated and clarified.

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October, 2011 Revision

The Student Handout has been reformatted and reworded for greater clarity and ease of use.  The Teacher Preparation Notes have been augmented with a more complete description of a Demonstration of Osmosis Using Chicken Eggs.

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August, 2010 revision

We have corrected an error in the materials listing in the Teacher Preparation Notes and made multiple revisions to improve the clarity and logical flow of the student handout.

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