Movement of Molecules Into Or Out of Cells

National Science Teachers Association
Type Category
Instructional Materials
Experiment/Lab Activity
This resource, vetted by NSTA curators, is provided to teachers along with suggested modifications to make it more in line with the vision of the NGSS. While not considered to be "fully aligned," the resources and expert recommendations provide teachers with concrete examples and expert guidance using the EQuIP rubric to adapted existing resources. Read more here.



Movement of Molecules Into and Out of Cells is one of a series of activities from "Scientific Argumentation in Biology:  30 Classroom Activities.  Movement of Molecules engages students in planning and carrying out investigations, modeling, engaging in argument from evidence, and communication.  After observing a figure of magnified red blood cells, and a figure of magnified red blood cells with sugar water added, students are presented with a question (Why do the red blood cells appear smaller) and three possible explanations.  Based on their chosen explanation and a set of available materials, they design an experiment to test their claim.  After engaging in an "Argumentation Session", they write an essay to support their explanation.  Teachers are encouraged to refer to the preface, introduction, assessment samples, and appendix provided in the full book for important background on the practice of argumentation and resources for classroom implementation.  The standards addressed in the lesson are also included in the teacher's notes.

Intended Audience

Educational Level
  • High School
  • Middle School
Access Restrictions

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Performance Expectations

MS-LS1-2 Develop and use a model to describe the function of a cell as a whole and ways parts of cells contribute to the function.

Clarification Statement: Emphasis is on the cell functioning as a whole system and the primary role of identified parts of the cell, specifically the nucleus, chloroplasts, mitochondria, cell membrane, and cell wall.

Assessment Boundary: Assessment of organelle structure/function relationships is limited to the cell wall and cell membrane. Assessment of the function of the other organelles is limited to their relationship to the whole cell. Assessment does not include the biochemical function of cells or cell parts.

This resource appears to be designed to build towards this performance expectation, though the resource developer has not explicitly stated so.

Comments about Including the Performance Expectation
This activity could serve as an opening to spark student learning leading up to this Performance Expectation, helping students understand structure and function of the cell membrane, and how it contributes to the structure and function of the cell. The resource guides students through the experimental design process as well as an authentic argumentation experience which culminates in a written essay that includes a claim, evidence, reasoning, and addresses counterarguments as well.

Science and Engineering Practices

This resource is explicitly designed to build towards this science and engineering practice.

Comments about Including the Science and Engineering Practice
This activity provides an opportunity for students to participate in argumentation. The graphic organizer, "Components of the Whiteboard" scaffolds students through the argumentation process and can be used in future argumentation activities. Students are given the choice of three claims from which to choose and develop their argument. Several questions are provided for the teacher to help assess whether their argument is convincing, and students share their work with others in a round-robin format. During the round-robin, one member of the group stays with the group's work and explains it to others, as they visit. The remaining group members go to other groups and listen and critique their arguments, resulting in a process during which every team evaluates each other's work.

This resource is explicitly designed to build towards this science and engineering practice.

Comments about Including the Science and Engineering Practice
This activity provides an introductory opportunity for teaching students about experimental design by asking a simple research question. Students are offered three possible explanations to answer the question of why the red blood cells appear smaller, from which to choose and plan their investigation accordingly. Students will need basic prior knowledge about cell structure and function and a basic understanding of experimental design terminology, e.g. the difference between independent and dependent variables. Students will be using chemical solutions and heat so they will need to be dressed in personal protective equipment and trained in lab safety practices.

Disciplinary Core Ideas

This resource is explicitly designed to build towards this disciplinary core idea.

Comments about Including the Disciplinary Core Idea
This activity provides a good opportunity to begin an exploration of how the cell membrane functions by using the dialysis tubing activity to engage in argumentation about what is happening at the microscopic level. After observing the effect of the sugar solution on their model cell, students will apply that knowledge to their observations of the sugar solution on the red blood cells. To reinforce the concept, the teacher could also include a demonstration of the effects of hypertonic, isotonic, and hypotonic solutions using the aquatic plant Anacharis.

Crosscutting Concepts

This resource is explicitly designed to build towards this crosscutting concept.

Comments about Including the Crosscutting Concept
The use of the model cell provided in the students investigations allows for an engaging opportunity for students to visualize, model, and describe osmosis and the function of the cell membrane in living organisms. Students use dialysis tubing to construct a model cell and immerse it in a sugar solution so they can indirectly observe the effects of osmosis and the function of the cell membrane. Directions are provided for an optional Benedict's test.

Resource Quality

  • Alignment to the Dimensions of the NGSS: This activity provides an authentic phenomenon that creates an opportunity for students to engage in three-dimensional learning. In this case, the phenomenon is osmosis and the goal is to understand the function of the cell membrane. Students participate in experimental design, argumentation, visualizing and modeling microscopic structures and systems. Teachers can use the format of this resource as a model to design future summative assessments on other topics.

  • Instructional Supports: By using a figure of red blood cells, and a hands-on model of a cell consisting of dialysis tubing to demonstrate osmosis, this activity provides an excellent, scientifically accurate context in which students can engage in three-dimensional learning. Students have opportunities to build on feedback from other students, and there is scaffolding in the form of a graphic organizer to support student engagement.

  • Monitoring Student Progress: The summative assessment offers an excellent opportunity to gather evidence of students' three-dimensional learning. A rubric and sample answer are provided. Furthermore, this could be used by the teacher as a model to design future three-dimensional assessments.

  • Quality of Technological Interactivity: This resource does not have a technology component.