A moment of recognition
8 April 2026
Our first-year students recently completed their practical microscopy assessment. After two full days of seeing thirty students work through pre-set microscope stations, I can report that many did excellent preparation. Some demonstrated truly impressive depth of knowledge, explaining mechanisms and procedures with confidence and accuracy.
This story is not about one of those students.
The Setup
By March, our students have encountered Gram staining through multiple channels. They attend my Introduction to Microbiology lecture, where I explain both Gram and Acid Fast staining, highlighting certain similarities in the principles of the procedures. They then have a compulsory introductory lecture specifically for the practical, going through Gram staining step-by-step again. They receive a practical handbook, also compulsory reading, which details the entire staining procedure. And finally, they perform the Gram stain themselves during the autumn practical, working in pairs, one staining a Gram-negative bacillus, the other a Gram-positive coccus.
After Christmas, they sit an MCQ exam testing their understanding of these procedures in detail.
Come March, they face the practical assessment: a microscope, a slide, an academic and a demonstrator. The task is straightforward: set up the microscope, visualize the specimen and tell us what you are looking at. We provide support and prompting. The specimens I provide are all Gram-stained bacterial samples. In fact, the good students know that, if you have an unknown specimen, you always start with the lowest magnification, 40× for our teaching microscopes, and I always acknowledge that this is correct, but that for the sample I have given them they will not see anything at that magnification, and that they should switch at least to the 400× magnification to start. I am always surprised how little students deduce from their surroundings. I appreciate that they are nervous. However, I only teach microbiology topics and I only do the microbiology lab practical with them. The slide they are handed has, depending on what it is, a red or a purple sticker on the side so that it is easier for me to see whether they got the classification right. The prompt that they need at least the 400× magnification to see anything meaningful. Paying close attention these are valuable clues that students could pick up on. But so few do. The number of times students, when finally visualising the bacterial sample, told me: "This is lung tissue!"
The Assessment
One particular student arrived at my station very happy and quite chatty. I immediately liked chatting with him. Unfortunately, his knowledge of the Gram staining procedure was rather limited. There was some understanding – fragments, really – but extracting it required considerable work. Specific questions. Prompting. Gentle corrections when answers went astray.
He knew very little about what the dyes actually do mechanistically or how the procedure functions at a molecular level. But, with substantial guidance, he eventually arrived at the correct classification for his specimen: it was a Gram-negative bacillus.
Progress. And he seemed proud that he got there in the end.
We then moved to a different practical he had done: the blood smear. Students had prepared horse blood smears in an earlier practical, staining them with eosin and hematoxylin. The key indicators of understanding here are relatively straightforward: red blood cells lack nuclei and appear pink-red from eosin staining, while white blood cells display purple-blue hematoxylin-stained nuclei. This contrast makes distinguishing red from white blood cells simple, and nuclear morphology allows classification of white blood cells into their various types: neutrophils with multi-lobed nuclei, lymphocytes with large round nuclei, monocytes with kidney-shaped nuclei, and so on.
The student began describing his blood smear. He remembered preparing the horse blood slide. I probed his understanding of the staining procedure's purpose and mechanism.
Again, knowledge was limited. Very limited. But he was clearly trying, genuinely engaged with the material despite struggling to recall specifics.
The Breakthrough
When I asked about the colours of red and white blood cells, he paused. Thought hard. The silence stretched. I could see him working through it, searching his memory for the connection.
Then something clicked. His face lit up with recognition. A proud smile appeared – the unmistakable expression of someone who has just made what they believe to be a brilliant intellectual connection. With a tone of genuine achievement and complete conviction, he announced:
"Pink! Red blood cells were stained reddish-pink! So that means they are Gram-positive!"
Somehow I felt heart-broken for failing him. But, in part by being forced by the demonstrator, who struggled to comprehend what she just had witnessed, there really was nothing else I could do.
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