Living Physics Portal: Random Motion Interactive Lecture Materials

Abstract: This module introduces the random walk immediately after 1D kinematics, so as to emphasize the importance of random motion in the life sciences and lay a foundation for students to think statistically as well as deterministically. It connects the random walk of individual molecules as the mechanism for gradient-driven flow. The module culminates in a two-week (6-hour) laboratory in which students actually observe random motion on the microscopic scale through video microscopy and digital image analysis.

Resource Types: In-class activity, Clicker question, Lecture materials

Authors:

Catherine Crouch

Swarthmore College

Ben Geller

Swarthmore College

TOPICS

Physics Topics:

Thermo & Stat Mech > Kinetic and Diffusive Processes > Brownian Motion, Diffusion, Kinetic Theory, Mean Collision Time, Mean Free Path, Viscosity

Life Sciences Topics:

Cross-cutting Biological Concepts > Causal Mechanisms > Physical Mechanisms

Cross-cutting Biological Concepts > Matter/energy Transfer & Transforms > Cross-membrane Transport, Material Flow

Chemistry Topics:

Gases > Ideal Gas Law

Math Topics:

Probability; Statistics

FILES Download3

Random Motion Module > Random Motion Interactive Lecture Materials

Random Motion Interactive Lecture Materials

Random Motion Slides 09102018.pptx

Random Motion Student Task Worksheets 09102018.docx

Random Motion Slides 09102018.pptx

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INSTRUCTOR GUIDE

IMPLEMENTATION

Duration: 3 sessions of 50 minutes per session.

Equipment required: No equipment needed

Specific equipment needed: For the laboratory, microscopes, digital cameras, and computers equipped to capture video from the cameras are needed. The microscopes we used were borrowed from our biology department and are otherwise used for their introductory or intermediate instructional laboratories. When we began teaching this lab, we had to purchase cameras because none of the introductory or intermediate biology laboratories used cameras with video capability. Since then a new intermediate systems biology course shares the cameras with us.

Basic implementation tips & tricks: Students may not be attentive to exactly what the quantities mean — for example, what is displayed by a histogram (counts vs. displacement from the starting location), or what flux is (they think of it as "flow" without grasping the quantitative definition). It's important to take the time to carefully walk through exactly what is shown in diagrams and what is denoted by symbols and terms.
The task worksheets are provided so that students have a place to write their work as well as a record of their thinking.

How does this resource fit into the flow of your course? The class and homework come immediately after 1D kinematics.

PEDAGOGY

Pedagogical approach: Peer Instruction / Think-Pair-Share; Conceptually-oriented activities; Mathematically-focused activities; Just-in-time Teaching

Skills / Competencies: Dimensional analysis; Multiple representations; Estimation; Evaluating models; Interdisciplinarity

What insights or realizations do you hope students gain from this resource? We want students to understand that diffusion and other gradient-driven motion arises when individual particles move with equal probability in either direction, but there are more of those particles in one place than in others, leading to the spreading of the distribution over time.

Why is this resource useful to life sciences students? Diffusion and gradient-driven flow are of critical importance to the life sciences. Understanding the underlying mechanism of these processes can be intrinsically satisfying; in addition, understanding that mechanism will allow students to properly model and computationally simulate such processes, as well as to understand them conceptually and distinguish gradient-driven statistical processes from deterministic processes.

DISCUSSION

SUBMISSION DETAILS

License: CC: BY-NC-SA - Attribution, No Commercial uses and Share Alike. Derivative works must have the same license

Last Edit Date: July 5, 2019