Lab safety & common sense — not mutually exclusive

In the September issue of this fabulous publication there is an idea for a first-day activity, taken from the Science Teachers’ Association of Ontario (STAO) virtual library, entitled Edible Candle. The article provides a means for students to understand the difference between observations and inferences using a teacher-made, authentic-looking “candle”— a peeled potato cylinder topped by a “wick” made of a thin piece of almond. Nuts are high in fat and will burn at least long enough for students to make observations of the lighted “candle”.

This is a fine demonstration — great fodder for the discussion mill.

What gets me are the safety considerations, which run to over 100 words:

Since this demo involves an open flame, it should be conducted only by the teacher.

  • Check the fire extinguisher before the class to ensure that it is working.
  • Before the demonstration, remind the students of the emergency procedures for fires (extinguisher use, fire exits, etc).
  • Before the demonstration, CHECK FOR SEVERE ALMOND ALLERGIES amongst your students. If allergies are a problem you could substitute a small piece of heavy white card for the slivered almond. The card should burn for the few seconds required for students to make their observations.
  • During the demonstration, keep a bucket of sand on hand to extinguish any accidental fire.

Let’s say I follow these to the letter: To ensure that the fire extinguisher is working, I’d have to try it; simply looking at the charging dial wouldn’t be enough. I’d have to do a run-through on the location of the classroom door(s) — the one(s) students just used to enter the room. And I’d have to go over evacuation of the building. I’d need to check for severe almond allergies — not regular almond allergies. And I would need a bucket of sand, presumably in case the fire extinguisher doesn’t work. What size bucket? And shouldn’t I check that the sand is free-flowing? What if it clumped?

And if this isn’t enough, the disposal instructions really take the cake:

The potato and almond should be disposed of in municipal compost if available. Otherwise, dispose of them in the garbage container.

Really? What was I going to do?  Make dinner?

Before you think that this is only a smart-aleck rant, let me tell you about a recent safety-related incident. I was cutting a less-than-pea-sized piece of sodium for a demonstration, when the scalpel blade broke. The broken-off piece twirled for maybe half a metre, before it landed on the floor in front of the students.

I never expected the blade to break. This kind of thing is called, I think, an “accident”.

But because typical, common sense-based safety precautions were followed, everything — and everyone — was fine. We all wore eye protection; students stood well back; I was sporting a lab coat and nitrile gloves; there was no water in the vicinity (Na reacts violently). And my work area was large and clutter-free.

I’m sorry, but I didn’t test the fire extinguisher or have a bucket of sand or check for severe sodium allergies.

Which raises the question — what is common sense? (Your mother might tell you that common sense is not so common.) Common sense is based on knowledge — and chemistry teachers are supposed to have chemistry knowledge. We get this knowledge from our teachers — in high school and in university; we also get it from teacher-training institutions. Further, I imagine that school boards cover this super-important topic, too.

Now that Teachers’ Colleges in Ontario involve a two year program (OISE/UT1 offers a Master of Teaching in Teaching(!) — who knew?), maybe extra time can be devoted to a common sense approach to safety. And by common sense, I mean chemistry knowledge-based, not safety rule book-based. The rewards of this kind of time investment are huge. Much more important, I think, than time spent parsing the latest Ministry of Education Guidelines or learning the edu-babble du jour.

Moving forward: I’m following common sense. I learned from the incident; I don’t cut alkali metals with a scalpel;
I use a (kitchen) paring knife with a robust blade.


  1. OISE/UT is the Ontario Institute for Studies in Education of the University of Toronto, Toronto, Ontario.

STAO response to Michael Jansen

We sent STAO this article and received this email:

STAO always welcomes comments regarding teaching resources. Thank you for forwarding the response from Michael Jansen. He suggested that the safety considerations were excessive. It is our assumption that each teacher will look at the safety considerations and then make a professional judgement as to which apply.

In my own classroom, the fire extinguisher is checked by school board personnel, and they then sign off that it is in working order. The bucket of sand is located inside my stock room in a place known to all department members. As for checking the room to make sure flammable liquids are present, these are stored in the flammable cabinet and only taken out when required for a particular activity. The emergency route is written on a colourful the safety plan. Since all of this is already in place, then I would simply proceed with the activity and enjoy that this resource was prepared for me by STAO, and that many more are available on the STAO website.

There is one safety consideration that was not included that in my opinion should have been. After blowing out the "edible candle", stall for time allowing the almond slice to cool down, before eating it. That happened to me ONLY ONCE!

Thank you for the feedback, and we will take your comments into consideration when preparing future resources, in an effort to make the safety considerations practical.


Dave Gervais

Chair, STAO Safety Committee