The Arizona STEM Acceleration Project

An Investigation of Osmosis

An Investigation of Osmosis

An 8-10 grade STEM lesson

Bryce Wolcott

03.26.2023

Notes for teachers

In this lesson, students will be introduced to the concept of osmosis, then investigate how solutions of various salt concentrations influence the size of plant cells.

List of Materials

• computer with internet access
• red onion epidermis
• forceps
• dropper
• distilled water
• 5% or higher percentage sodium chloride (table salt) solution
• paper towels
• microscope
• microscope slide & cover slip
• stamp and ink pad (for teacher)
• blank paper

Arizona Science Standards

Arizona Technology Standards

HS.L1U1.20: Ask questions and/or make predictions based on observations and evidence to demonstrate how cellular organization, structure, and function allow organisms to maintain homeostasis.

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9-12.3.a. Students plan and employ effective research strategies to locate information and other resources for their intellectual and/or creative pursuits.

Objective:

Conduct an investigation to examine the effect of hypotonic and hypertonic solutions on plant cells.

Agenda (two 50-minute class periods)

Day 1 (50 minutes)

• Anticipatory set
• Osmosis content (reading and video)

Day 2 (50 minutes)

• Osmosis Lab

Driving Questions

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1. Why do grocery store owners spray fresh fruits and vegetables with water?

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2. If a shipwrecked crew drinks sea water, they will probably die. Why?

Osmosis content

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Read the lesson on Osmosis found here. Be sure to watch the video at the end.

Click “View Practice” at the bottom of the screen and complete a practice session until you reach a Skill Level of Mastery.

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Osmosis Lab Instructions

• Completing an introductory activity (on a different day) where students learn how to use a microscope can help students focus on the concept of osmosis (rather than the microscope itself) during this lesson.
• Groups of 2-3 students to share a microscope work well for this lab.
• Click here for an instruction sheet for this lab.

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Assessment

1. Day 1 Adaptive Practice on Osmosis.
2. Day 2 Interpretation Questions on the lab instruction sheet.

Differentiation

1. Students could conduct a similar investigation using pieces of potato, rather than onion cells. This avoids the complication of using a microscope to make observations.

Remediation

Extension/Enrichment

1. Students could perform this investigation with animal cells by harvesting cells from the buccal mucosa (inside of the cheek) using a toothpick, then compare/contrast the results.