In my NQT year I took a 5th year class. Schools don’t like to do that, to give Y11 to a shiny new teacher, but they were short of Chemists (nothing changes). Of all my classes I worried about them most, this was an important year for them, it was their “chance” I would get other chances they wouldn’t. I prepared my lessons well BUT struggled to win them over, it would take time and time we didn’t have. They always arrived slowly, ambled in, took ages to get their books out and coats off – in fact anything to delay learning and there were always niggles – forgotten books, forgotten pens, do I have to wear these goggles? ……teachers know this scenario well.
The timetable didn’t help Friday last lesson and Monday first lesson is effectively a double split over a weekend and I soon learnt to do some practicals and demos Friday and the theory on Monday such was their attention span or lack. I did rely on the lab technician as do all science staff – these folk are unsung heroes, and Kathy was such for us. However her hours changed and she left early on a Friday but diligently left me my materials.
It was one such Friday after demonstrations of the Halogens ( GroupVII) and a class experiment with iodine solution the class left and I was happy, it had gone well after the usual shaninkins. However just as I was locking up this upstairs lab, I realised leaving even respectably small quantities of chlorine and bromine and iodine wasn’t good and no one else was clearing away. No one had told me about Hazcards, or I had already forgotten. These cards have alls sorts of info per chemical…. how to make, use dispose and treat spills or ingestion etc). Still, me a graduate chemist of a fairly prestigious University tried to recall on a Friday after a long week how to dispose of anything too risky. I seemed to think was possible to dissolve the excesses in alkali. Tentatively I did so in the fume cupboard mixing with sodium hydroxide and washing down the sink (chemists forgive me). Just as I left the lab I noticed at the back a load of tubes of Iodine water the class themselves had used to do similar tests to my demo of the other halogens. I had used up all my alkali and so without further thinking I dissolved this into another alkali and swilled down the sink on the teacher’s bench. After all iodine is much less hazardous! [PS DO NOT try this at home!]
Twas on the Monday morning they drifted in after assembly half awake and I greeted them cheerfully cleaning the blackboard with my dusty cloth and then flinging it down the bench with a little much gusto. The cloth slid gracefully into the sink and there followed an incredibly loud bang, a very sharp crack, a significant puff of smoke and a small purple cloud. Even I took cover for a moment. – whence the cloud disappeared I looked out to find not one pupil in my classroom. As I walked from the front bench I found each Y11 cowered on their knees, heads in their hands, behind their bench in total silence.
What had happened was the sink like many an old school facility didn’t drain well and some of my waste solution stayed around the rim of the drain and dried out as the water evaporated over the weekend and out crystallised probably the tiniest amount of Nitrogen tri-iodide – an explosive substance detonated as they say with the touch of a feather, it was used in those devil bangers and I suspect little cap guns when I was little.
Somewhat embarrassed I did explain this to my Head of Chemistry (my Head of Science wanted the recipe – typical Physicist) but any embarrassment was more than made up for by my class. Once they emerged from their defensive positions they worked their socks off and did so with through the year. I never made that chemistry mistake again, whether I used that disciplinary technique is another question
Lab technicians are wonderful folk but they store stuff along with storing knowledge, I learnt that day to double check and do my research carefully.
Discipline is vital in schools, good behaviour in lessons but it need not come from shouting, or serious control or deep sarcasm, or worse, persistent nagging. Preparing something interesting to learn and working hard with relationships was what I always had to do, but I did need the occasional extra hand from a head of year, a head of department or a small explosive.
[Beware, Nitrogen Triodide is a highly sensitive contact explosive, completely unpredictable and the iodine vapour a hazardous gas DO NOT try this at home or work or ….]