Microscopy is the single biggest challenge for students coming into my Pathogenic Microbiology laboratory, despite its regular use in multiple prerequisite classes. Each semester, I ask my students to complete a quick self-assessment on the first day of lab, and the vast majority of students “strongly agree” that they are able to use brightfield microscopy…until I ask them to prove it.

Student perceptions of their ability to use brightfield microscopy at the beginning (pre-class) and end (post-class) of my Pathogenic Microbiology laboratory. As part of the post-class assessment, students are asked to re-rank their abilities from the beginning of the semester (reflection).

Immediately following the self-assessment, I ask my students to Gram stain a mixed culture of E. coli and S. aureus; however, only 59% of students are able to find cells on the microscope. Of the other 41%, some blame the equipment or decide their failure was a fluke, but many hide their inability out of embarrassment or apathy. Very few ask for help.

It isn’t until they start trying to identify unknown bacterial cultures that the students find themselves in the Dunning-Kruger Valley of Despair. Their ability to Gram stain becomes frustratingly inconsistent; some days, everything works perfectly. Other days…not so much.

The Problem

I suspect that the perceived intuitiveness of microscopy is the greatest contributor to microscopy difficulties in teaching laboratories. If somebody cannot find an image, it couldn’t possibly be due to inexperience, right? After all, light microscopes are simple in operation- you place a microscope slide on the stage, look through the ocular lens, and adjust a knob until you see something.

The first student response to microscopy failure is to blame the equipment. Students have an undeserved reputation for being excessively hard on microscopes, while many departments have a well-deserved reputation for not maintaining or replacing their equipment (not mine, btw). Over time, students, TAs, and even instructors can find themselves blaming the equipment, but teaching microscopes are difficult to actually break. More commonly, somebody has naively moved the diaphragm outside of its workable range or inadvertently turned the stage-height safety thumb screw, preventing the stage from ever moving the specimen into the plane of focus. Every semester, I sort through the microscopes labeled “broken” and find that the majority are perfectly functional with minor readjustment.

The second (and worst) student response is to hide in embarrassment. Imposter syndrome sets in quickly when somebody fails to do something they think is simple, and microscopy is actually more complicated than they realize. This problem culminated one semester when, during the final week of the semester, a defeated student admitted they have not been able to use the microscope all semester, and instead relied entirely on their neighbors. It may be (re: is) unhealthy, but I took it as a personal failure- I didn’t effectively communicate one of the most fundamental skills in microbiology, nor did I notice until it was too late.

My Solution

My new approach to teaching microscopy is to “break” the microscopes. Before the second day of class, I crank every knob and dial on each of the microscopes to the extremes. When the students come in, I tell the students that I have “broken” every single microscope in the room. I then challenge the students to fix them using this troubleshooting guide, video tutorials, active demonstrations, their prior knowledge, and a prepared Gram stain slide. I haven’t quantified this exercise yet, but it already seems to be much more effective than the traditional method of teaching them how to really use a microscope. It also gives them a toolbox to refer to the next time they struggle with a microscope.