Lesson Background & Justification:
Cell transport is the movement of materials across cell membranes. Cell transport can be performed via passive and active transport depending on whether the action does or does not require energy. Passive transport (eg. diffusion and osmosis) is an example of diffusion does not require energy whereas Active Transport (eg. ion transport) requires energy to proceed. Passive transport will be initially be explored in this first of a two part lesson sequence in the effort to scaffold the materials gradually and logically to comprehend how and why materials can be transported in and out the cell at varied frequencies.
Note: This lesson, the second part of Of Cellular Transport and The Cerebrum, reviews passive transport processes & introduces active transport processes to students in the effort to construct a more realistic simulation of activities in neurons that occur during excessive alcohol consumption.
In the effort to prepare for this lesson, I make certain that I have the following items in place:
a) A class set of 3D Molecular Design: Phospholipid and Membrane Transport Field Test Kit (1 per student group of 4)
b) Student lab books.
Common Core and NGSS Standards:
SP4- Analyzing and interpreting data.
SP2- Developing and Using Models.
HS-LS13: Plan and conduct an investigation to provide evidence that feedback mechanisms maintain homeostasis.
Modeling is the process by which scientists represent ideas about the natural world to each other, and then collaboratively make changes to these representations over time in response to new evidence and understandings. It is intimately connected to other scientific processes (asking questions, communicating information, etc.) and improves students ability to recall scientific jargon through association. In the classroom, it is important that teachers engage students in modeling practices, to set the foundation of success in a lesson or instructional unit. In this lesson modeling is used in concert with other science practices in the classroom to promote students’ reasoning and understanding of core science idea presented (mechanisms of maintaining homeostasis).
Section Instructional Sequence:
In this section of the lesson, my goals are to review the impact of alcohol consumption on the human brain via passive transport processes and to expound upon the effects incurred due to active transport activities. The idea is to introduce students to the concept of active transport (ion movement in particular) and to provide them with tools to effectively model the exit of vital ions and water from neurons and cells in general during alcohol consumption. This activity proceeds as follows:
a) Slide 1: State: "Let's take the time to review how extreme alcohol consumption leads to a dehydrated brain". Discuss students' notes and models from previous lesson aloud. Next, share that they will watch a clip to iterate these points and to build on to their understanding of why alcohol creates a physical state referred to as a hangover. Read the "Be mindful..." statement to students & proceed to play the following video clip:
b) Discuss new revelations with students post video and inquire about materials dispensed from the body during a hangover. Ask: "Why is this problematic?" and share that we will learn more about how these items move in and out of the neuron compare to water and ethanol's movement.
c) Students will be defining the terms on slide 2 during the video to construct some new understandings. Slide 2: Instruct students to record the terms presented on the slide & to define them as the video Cellular Transport Processes plays and progresses. Emphasize that these terms will help them to construct a scientific explanation for alcohol's effects on the brain in the lesson's totality. Play the video and pause the video when necessary for proper recording. Review definitions post video.
d) Slide 3: State: "Now let's take the opportunity to simulate what these processes look like using our own neuron models". Provide each pair of students (or larger groups if there are cost limitations) with a Plasma Membrane Transport Kit and advance one task at a time on the slide. Give students 10 minutes with each task. Circulate and correct any misrepresentations throughout.
See reflection for student work examples.
Note: Slide 4 demonstrates how to properly simulate active transport of Sodium and Potassium ions with the kit. This slide is hyperlinked in step 4 to show students proper manipulation before they fully execute the task.
Section Instructional Sequence:
In this section of the lesson, my goal is to provide students to assess students ability to explain via illustration and annotations how the natural homeostatic transport processes of the cell impacts an organism systematically and produces symptoms associated with a hangover. This activity proceeds as follows:
a) Slide 5: State "Now that we understand how these cellular and homeostatic processes work independently, let's pull this all together collectively to tell the molecular and cellular story of alcohol's impact on the human brain." Be certain to emphasize why systemic impact is the ultimate stage as we are a hierarchy of materials that show emergent properties from the molecular level on up.
b) Read the assignment specifics aloud to the class and share that they will have up to 30 minutes to complete this task. Circulate to keep students on task. Evaluate students stories based on rubric projected on the slide.
See Extension Reflection for examples of completed products.