Hands-on Activity Cell Membrane Experimental Design

Quick Look

Grade Level: 9 (9-12)

Time Required: 45 minutes

Expendable Cost/Group: US $5.00

Group Size: 0

Activity Dependency:

Subject Areas: Algebra, Biology, Chemistry, Data Analysis and Probability, Life Science, Measurement, Problem Solving, Reasoning and Proof, Science and Technology

NGSS Performance Expectations:

NGSS Three Dimensional Triangle

Cartoon drawing of a boy, microscope and cell.
Thinking about experimentation.
Copyright © 2004 Microsoft Corporation, One Microsoft Way, Redmond, WA 98052-6399 USA. All rights reserved.


The final activity of this unit, which integrates the Keepers of the Gate unit through the Go Public challenge, involves students taking part in experimental design. They design a lab that answers the challenge question: "You are spending the night with your grandmother when your throat starts to feel sore. Your grandma tells you to gargle with salt water and it will feel much better. Thinking this is an old wive's tale, you scoff, but when you try it later that night it works! Why?" Students must have their plan approved by the instructor before they begin. A formal lab write-up is due as part of the laboratory investigation.
This engineering curriculum aligns to Next Generation Science Standards (NGSS).

Engineering Connection

Students design a lab using all the expertise they have gained through the unit. The lab analysis must help them answer the Grand Challenge question. By formulating their own plans for the lab, students are participating in the engineering design process: engineers use their previous knowledge and personal experience to aid the design of novel solutions to problems. Engineers also utilize experimental design to further test their solutions. Students use their previous knowledge from the earlier lessons and activities to facilitate their lab design process.

Learning Objectives

After this activity, students should be able to:

  • Design and conduct an experiment to help answer the challenge question.
  • Write a formal lab report for the experiment.
  • Explain how the designed lab furthers their understanding of the engineering design process.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

NGSS Performance Expectation

MS-ETS1-3. Analyze data from tests to determine similarities and differences among several design solutions to identify the best characteristics of each that can be combined into a new solution to better meet the criteria for success. (Grades 6 - 8)

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This activity focuses on the following Three Dimensional Learning aspects of NGSS:
Science & Engineering Practices Disciplinary Core Ideas Crosscutting Concepts
Analyze and interpret data to determine similarities and differences in findings.

Alignment agreement:

There are systematic processes for evaluating solutions with respect to how well they meet the criteria and constraints of a problem.

Alignment agreement:

Sometimes parts of different solutions can be combined to create a solution that is better than any of its predecessors.

Alignment agreement:

Although one design may not perform the best across all tests, identifying the characteristics of the design that performed the best in each test can provide useful information for the redesign process—that is, some of the characteristics may be incorporated into the new design.

Alignment agreement:

  • Identify the design problem to solve and decide whether or not to address it. (Grades 9 - 12) More Details

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  • Optimize a design by addressing desired qualities within criteria and constraints. (Grades 9 - 12) More Details

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Materials List

Each group needs:

Possible materials:

  • potato slices (8 per group)
  • 4 cups
  • 4 concentrations of salt ( NaCl) dissolved in water: 100 ml of each per group

0 % - pure distilled water

5% - 5 g NaCl/ 100 g solution

10% - 10g NaCl/ 100 g solution

15% - 15g NaCl/100 g solution

Worksheets and Attachments

Visit [www.teachengineering.org/activities/view/van_membrane_activity5] to print or download.


At the start of this unit, you were presented with a challenge question: You are spending the night with your grandmother when your throat starts to feel sore. Your grandma tells you to gargle with salt water and it will feel much better. Thinking this is an old wive's tale, you scoff, but when you try it later that night it works! Why?"

Now, like an engineer, you will apply what you know about cells to design an experiment to further answer the challenge question. What experiment can you design? How will your results support your answer? These are questions you must ask yourself in the scientific process. Engineers must utilize previous knowledge and personal experience to aid in the design process.

Engineers often perform scientific experiments to gather research pertaining to a phenomenon they are studying as part of finding solutions to a real-life problem. In this case, the problem is a sore throat. Your job is to figure out why salt water can help a sore throat and to propose a possible better solution than salt water. The information that you have just learned during these past few lessons and activities will greatly help you in your thinking process when you attempt to design your plan for the lab in this Go Public portion of the legacy cycle.



Students work together in research teams to design experiments that show both the qualitative and quantitative effects of osmosis. They include demonstrations of solutions that are hypotonic, hypertonic and isotonic. A formal lab report is due at the conclusion of the experiment.

Before the Activity

With the Students

Using strands of potatoes and different concentrations of NaCl solutions, have students design experiments to explore osmosis in raw potatoes. Explain that this closely models what happens to cells in their throats when gargling with salt water. Use controls in the experiments and collect and organize the data in meaningful ways.


Worksheets: Have students use the worksheet to guide their lab experiments. Review their answers to the worksheet questions to evaluate their comprehension of the concepts.

Lab Report: Require students to prepare formal lab reports to turn in at the conclusion of the lab. Review their reports to assess their mastery of the subject matter and concepts.


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© 2013 by Regents of the University of Colorado; original © 2010 Vanderbilt University


Melinda M. Higgins

Supporting Program

VU Bioengineering RET Program, School of Engineering, Vanderbilt University


The contents of this digital library curriculum were developed under National Science Foundation RET grant nos. 0338092 and 0742871. However, these contents do not necessarily represent the policies of the NSF, and you should not assume endorsement by the federal government.

Last modified: September 5, 2017

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