High School Biology: The Immune System

As part of my SAT-level high school biology classes study of the immune system, the students grew bacterial cultures taken from their bodies.  This was an extremely simple experiment and only took a small amount of class time.

  • Each student got two commercially prepared petri dishes with bacterial growth medium, and divided each petri dish into two parts (so that they could take 3 samples and have a control).
  • I showed them very basic swabbing technique and then they each chose 3 parts of their body to sample.
  • We put the petri dishes in a warm, dark place for a week and then took a look at the results.

My primary goal with this activity was for the students to get a tiny, but vivid peek into the bacterial diversity that we each possess.  I also wanted them to have at least a little bit of experience with microbial culturing techniques.  Overall, I’m reasonably happy with how this activity went.  Students definitely gained an appreciation for how many microorganisms make their homes on our bodies.  My concern main is that the experiment was too easy and simple for high school students.  In general, I want lab activities to challenge students to think deeply, and this one really didn’t meet that goal.  On the other hand, given the technical challenges of studying the immune system, that may not be possible for this particular topic.

If you are a biology teacher and have an immune system lab that you love, I’d be exceedingly interested in hearing about it!

A close-up showing the difference between the control half of a petri dish and the swabbed portion.
A close-up showing the difference between the control half of a petri dish and the swabbed portion.
The control and three samples from one student.
The control and three samples from one student.
Bacteria grown from two different parts of the same student.
Bacteria grown from two different parts of the same student.
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