Weathering the Storm . . . of Chemistry Labs

Good day, gentle readers:

Let me start by telling a story that, at first blush, has nothing to do with chemistry teaching.

A bunch of years ago, my friend Ravi and I were at a summer cottage, together with our spouses. I like canoeing. I coaxed Ravi, a non-swimmer, into an old, less-than-lakeworthy boat for a three hour tour¹.

My insistence on a PFD² was prescient.

On our way back, for reasons that don’t bear repeating, the canoe tipped. We were tossed into the drink, bobbing in the waves. Ravi’s high-diopter glasses disappeared, quicker than you could say “one thousand dollars”. This was fortunate; he couldn’t see how far we were from shore. In spite of the panic, Ravi wanted to save the canoe. As it was sinking, Ravi held on, trying his best to prevent the boat’s descent.

Remember the scene in Titanic where the ship slowly disappears? That’s what I was thinkin’ as the canoe slipped from view in 60’ of green, Ontario lake water.

We swam to shore, where a kind-hearted citizen took us home in his boat, which, incidentally did not sink.³

What does this have to do with chemistry teaching?

Everything and nothing.

In my student days, I struggled consistently with poor understanding of just about every Chemistry experiment. The best I could do was “add 3 mL of 1 M HCl to the contents of test tube B, prepared in step 1, and record observations in Table 2”. I was hanging on to sub-standard comprehension, while my love of Chemistry slipped away.

For sure, I shoulder some blame⁴, but the design of the experiments was . . . how shall I say it . . . less-than-understanding-worthy.

The experiments of my high school days were more than recipe-based. We followed a procedure, and in the case of quantitative work, recorded our data in a pre-formatted table. When it came to calculations, we were instructed—I’m not kidding—to “subtract line 2 from line 1”  . . . you get the idea.

Upside: When tax-time rolled around, I was good to go.

I remember carrying out “discovery” labs, only to discover that I didn’t have a clue.

I remember the supreme frustration of trying to make sense of results, in a fog of poor experimentation and poorer comprehension. When it came to the lab report, I was at sea, clinging to a sinking ship.

My undergraduate experience in the late 70s/early 80s was similar. With a few mind-expanding exceptions, like identifying unknown organic compounds, we pretty much followed a set of instructions to arrive at the desired outcome.

It was as a summer research student that I learned to be a real chemist. I needed to think—sometimes creatively. I needed to make judgement calls. Working on a professor’s research team changed me out of short pants—and into a lab coat.

As a newly minted teacher, I began with the cookbook labs I was used to. It didn’t take long to see that Betty Crocker-ing through an experiment that was supposed to be “science” didn’t accomplish much. I hate to admit this, but it was a relief to see students struggling as I had.

Slowly, over many years, my approach evolved. I thought. I stayed after school, looking for better/faster/cheaper/more efficient ways of fostering understanding. I started a co-curricular Chemistry Education Research Group (CERG) to produce new-and-improved laboratory activities and demonstrations, with students at my side. Students took pride in seeing the fruit of their labor in next year’s handouts.  Many times my ideas were simply re-makes of the original. But hey . . . ideas aren’t copyrighted. 

I made some useful changes:

• removal of a step-by-step procedure, unless required for safety, or if students are wading into the totally unfamiliar;
• placing a strong focus on pre-lab discussion and on pre-lab questions, to establish the what, why and how;
• data tables are still provided, but they are totally blank—extra cells provided, just to throw ‘em off;
• we have a thorough post-lab discussion, ensuring that everyone knows how to deal with data analysis and post-lab questions

Rather than make laboratory work easier, this approach makes it, in many ways, more challenging. Our discussions demand that students engage: listen, take notes, ask questions, understand—important techniques now, more than ever. I see students doing chemistry—not a procedure. This approach facilitates more interesting questions, particularly concerning data analysis, and “how can we build on, or extend, this investigation?”. 

Laboratory activities at Crescent School have evolved into a cohesive body of practical—hands-on and minds-on (!)—work that is captivating, useful, and driven by empirical evidence.

We do science.

Most experiments are short—not cumbersome, dread-worthy, 70 minute-long affairs. Sometimes things are done as teacher demonstrations, worthy of Socrates in the agora-equivalent of a fume hood⁵. On the Physical Chemistry side, by the end of Grade 11, students have determined, among other things, the  molar volume of H₂and of O₂, the simplest formula of zinc chloride⁶, the molar volume of acetone⁷ (Dumas method), molar mass of unknown solid acid (titration), molar mass of propane⁸ (downward displacement of water), molar mass of CO₂ and of CH₄ contained in a 2-L soda bottle.

Incredible stuff, this figuring out molar mass without a periodic table.

Analytical Chemistry-wise, our flagship is the spectrophotometric determination of the % (m/m) of Allura Red AC (food colouring) in Red Velvet cake mix.

Students have observed limiting/excess reagent, determined the solubility of CO₂ in water—qualitatively and semi-quantitatively, determined percentage yield and percentage purity, identified unknowns using a series of tests . . . the list goes on.

My AP chemists do even cooler things.

Why am I telling you this?

To inspire you to make your laboratory program the cornerstone. To show your students that Chemistry is everywhere; that Chemistry is about thinking; that Chemistry is evidence-based; that good Chemistry will always have more questions than answers—and that questions are more important than answers.

I weathered the storm; our laboratory program is on an even keel.

May peace be with you.