Neurons are so Impulsive! (Day 2)

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Objective

Students will develop and use a model to explain how nerve impulses are initiated, propagated and terminated along neurons.

Big Idea

Electrostimuation of a neuron requires the recruitment of specific chemicals or mechanical energy to stimulate it, intracellular and extracellular ions for its electrical propagation and the release of neurotransmitters to complete an action potential.

Introduction

Lesson Background & Justification:

       An Action Potential is the change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell. This impulse generated, as a result gained momentum, propagates down the axon and finishes with the release of neurotransmitters stored in vesicles at the end of the axon. This ultimately and consequently stimulates the post synaptic cell and repeats the process so that a message may transmitted from short and long distances within the body. In this lesson, students explore the power of positive ions within the cell to understand how electrical impulses are perpetuated and sustained over great distances within the human body.

Lesson Preparations:

 In the effort to prepare for this lesson, I make certain that I have the following items in place: 

a) A class set of laptops or Ipads. Student BYOT (bring your own technologies) are suitable as well.

b) Student lab books.

c) Class copies of students evaluation worksheets. (See Evaluation Section/attachment)

 Common Core and NGSS Standards:

HS-PS2-6: Communicate scientific and technical information about why the molecular-level structure is important in the functioning of designed materials. 

SP2- Developing and using models.  

Standards Rationale:

      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 (neuron transmission of impulse via action potentials).  

  

Extend

60 minutes

Section Sequence:

      In the section of the lesson, my goal is to provide students with an opportunity to discover how scientists measure the electricity generated during the impulses propagated in a nerve cells during an action potential. The idea is to show them where the peaks that arrive on the corresponding action potential graphs stem from so that they are comfortable with interpreting them in the next activity of this section. I proceed as follows:

 a) State: Today, we are going to continue building our understanding of action potentials and take it a step further. Provide every student pair with a laptop or technology equivalent. 

b) Direct students to the HHMI Interactive Activity:  Electrical Activity of Neuron Interactive and to explore each page and accompanying videos. Inside their lab books, students are to create and record one summary sentence for each interactive slide. 

c) Post activity, project the interactive on the screen and move from one slide to the next while asking for at least two student summaries for each one as they are presented. Clarify any misconceptions.

d) Discuss as a class how students know what they know about action potentials. 

e) Slide 3: Provide all students with a copy of the action potential graph and use the board to review what the peaks and valleys of the graph signify. Bring students attention to the words of the action potential that represents specific frames of the graph. Instruct students to use the pink box to illustrate the corresponding actions that are occurring along the axon of the neuron.

f) Advance slide to unveil the images and review with students.  

Standards Covered:

HS-PS2-6: Communicate scientific and technical information about why the molecular-level structure is important in the functioning of designed materials. 

SP2- Developing and using models.  

Evaluate

30 minutes

Section Sequence:

      In the section of the lesson, my goal is to evaluate student's understanding of the lesson. I proceed as follows:

a) Provide students with copies of the practice Action Potential Practice Sheet.

b) Instruct for students to complete them individually.

c) Instruct students to swap papers and review responses with students as they peer edit and grade.

Evaluation Alternative:

    As an alternative to a worksheet, students can be assigned the option of illustrating the the entire action potential process with emphasis on bringing clarity to the molecular events that translate into electrical energy that we are capable of measuring as witnessed in the extension activity. (See student work examples). This work is collected and graded individually.  

 Standards Covered:

HS-PS2-6: Communicate scientific and technical information about why the molecular-level structure is important in the functioning of designed materials.