Friday, 24 of March of 2017

Seeing the Invisible: Microbe Hunters!

Seeing the Invisible: Microbe Hunters! is a program for 3rd and 4th grade students run by Prof. Joshua Kritzer of Tufts University.  It emphasizes the scientific method by introducing students to something they cannot see:  microbes.  Because they cannot be directly seen, students must design experiments and interpret results in order to study them.

The program consists of two in-class sessions.  In the first, we discuss what microbes are, and how we know they are there despite the fact that we cannot see a single microbe.  The relationship between single, invisible microbes and visible colonies of many microbes is reinforced through role-playing and mathematical games about exponential growth.

exponential1

exponetnial2

After connecting one invisible microbe to visible colonies, students swab their environment to hunt for microbes.  Students draw a prediction and then perform a controlled experiment using sterile cotton swabs and real microbial growth plates.

swabbing

We grow the plates back in our lab, then seal them securely to make them safe for students to handle.  We also prepare sealed microscope slides of the students’ own cultured microbes.

prepping

In the second session, each student documents his or her own experiment and classifies any microbes they observe.  Together, the class graphs their collective results and makes their own conclusions about microbes from their experiments.  Finally, we view microbes using a projection microscope to cement the relationship between individual, invisible cells and the fuzzy colonies they can now observe on their Petri plates.

results

plate5

This workshop is available on a limited basis in 2015-2016.  For details, contact:

Karen O’Hagan, Outreach Coordinator
Tufts University Department of Chemistry
karen.ohagan@tufts.edu
617.627.3729