Teaching has its moments that bring a smile to your face. Today held just such a moment.
In preparation for their upcoming Cambridge exams, my AS-Biology students have been recapping their microscope skills (how to use eyepiece graticules and stage micrometers, etc.). Having just enough apparatus for each current student, I was suitably unimpressed when one of them shouted out:
"Ma'am, I can't see through the x40 objective".
As my stomach dropped, I walked over to assess the situation. Indeed, x4 and x10 were perfect, but x40 was entirely obscured. Hypothesis: probable cracked objective that could only be repaired next year.
In my second lab today, the same thing happened with a different student and a different microscope. Wondering just exactly when my students had become microscope cracking marauders, I strolled over to the offending object. It was then that something caught my eye.
The ceiling light glinted off the top of the eyepiece making a rather strange pattern. I removed the eyepiece and stared up at it. Lo and behold, the "crack" cascading across the view at x40 (thus, magnified to x400) was nothing more than eyelash streaks on the ocular lens, caused by anxious students pushing their eyes against the microscope. I rubbed it off quickly and quietly using the hem of my shirt and pronounced it to be "fixed".
I was let off the hook easy on that one :-)
Driving home, I realised that I often put my eye to every single microscope many times during one lab session to help out the students when they need it. Being a little bit obsessive when it comes to hygiene, I let out an internal, "Ewww", at the thought of all the skin grease my ocular orbits had come into contact with.
First stop on arriving home: basin full of water and good old Sunlight soap!
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