Hands-on Activity Cell Membrane Experimental Design

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: Next Generation Science Standards - Science

International Technology and Engineering Educators Association - Technology

State Standards

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

• balances
• Keepers of the Gate Design Challenge Student Worksheet, one per student

Worksheets and Attachments

Introduction/Motivation

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.

Procedure

Background

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

• Gather materials necessary for the lab.
• Make copies of the Keepers of the Gate Design Challenge Student Worksheet.

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.

Assessment

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.

Copyright

Contributors

Supporting Program

Acknowledgements

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.