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The Length Constant

by Greg Crowther


This song was written for BBIO 351 at the University of Washington Bothell. It helps students understand the passive spread of electrical signals through neurons.


The length constant, sometimes called lambda
(Another word spelled with L)
Is a root of a ratio of resistances.
Which resistances? I will tell....

Rm over Ri!
Rm over Ri!
Which way is easier for the ions to fly?
Rm over Ri!

Other Files

MP3 (demo)

music video

sheet music (with melody play-back)

Lesson Plan

Songs like this one can be used during class meetings and/or in homework assignments. Either way, the song will be most impactful if students DO something with it, as opposed to just listening.

An initial, simple follow-up activity could be to answer the study questions below. A more extensive interaction with the song might entail (A) learning to sing it, using the audio file and/or sheet music as a guide, or (B) designing kinesthetic movements ("dance moves") to embody it. The latter activity should begin with students identifying the most important or most challenging content of the song, and deciding how to illustrate that particular content.

Study Questions

(1) What do Rm and Ri stand for?

(2) How do (a) myelin and (b) axon diameter affect Rm and/or Ri?

(3) What units does the length constant have?

(Answers may be found on the answers page.)