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Aquarium fish by Kathie McMillan Via Flickr: "We Look About Us, Book 1" of the Pathways to Science Series by Gerald S. Craig and Agnes Burke. Intended for the first grade level. Copyright 1933 by Craig and Burke, published by Ginn and Company.
What is the point of practical chemistry in schools?
In which I attempt to do myself out of a job…
When we learn science in school we do practical work. It’s seen as a valuable part of the process, supplementing the classroom work and bringing the subject to life. In the UK we do rather a lot of it compared to other countries, and many educators would argue that we still don’t do enough. Ask any adult what they remember about their science lessons at school from years previously and practical work will feature pretty strongly in their memories. Sometimes it’s the only memory.
And yet… There are good arguments for getting rid of practical work. Most obviously there is cost. You need all the resources that the English department has, plus chemicals, glassware and other equipment. You need extra staff (we technicians might not be paid much but we still cost money). In some countries schools don’t have technicians, so teachers need to do the job - spending time that they’re not teaching. There are classroom management issues (do you really trust that class to use Bunsen burners without injuring themselves?).
Crucially there is the question: what do students actually learn in practical lessons? In my experience many students see practicals as play time, and switch off from learning. Others focus on the practical work and lose the connection with the learning objective it’s supposed to reinforce. Under the curriculum in England at the moment it’s very tempting to do the Required Practicals just to tick the box, rather than treating them as a learning experience.
Surely we’d be better off doing demos and watching videos? No opportunity for students to foul up and you can repeat if necessary. Instead of spending a lesson failing to collect data you can present them with a pristine set of data, and you can spend time getting them to plot the graph properly.
Before I go and collect my P45, here’s the alternative: we teach students how to do practical work as an end in itself. This starts with drilling safe practice until it becomes instinctive - wearing safety glasses at all times, standing up and following instructions to the letter. This isn’t new - many schools issue “Bunsen Burner Licenses” to their Year 7’s when they are judged to be able to use them safely. We can move on to handling glassware and equipment properly and confidently. They need to handle chemicals safely - measuring them out without spilling (and clearing up if they do), recapping bottles as soon as possible, and generally treating potentially dangerous substances with respect. It should be second nature for them to pay attention to their experiments and to record their data properly (as per the instructions).
What’s the point of this change in emphasis? Even if students don’t go into science after leaving school we are giving them skills and an attitude that are useful in many fields. For those going on to university science courses or technical apprenticeships they will have the confidence to get on with and enjoy their practical work immediately.
This is a huge area that needs a more extensive treatment than this piece, with examples and references. But I hope it starts a debate.
Next time: why we are letting down our students with rubbish practicals (with examples).
In this article, I've written about the fundamental forces in nature, their basic properties, relative comparison, and the domains where they operate.
Parallax is an optical phenomenon. The parallax method can be used to measure the distances of a faraway object, like a planet or a star.
What is parallax? Measurement of large distances using parallax method.
The difference between accuracy and precision, along with different types of errors that might be there in the final results.
Difference between accuracy and precision. What are errors and types of errors.
In this article, I've written about the physical quantities, units, SI units, and some guidelines – how to use SI unit symbols and prefixes?
Physical Quantities and SI Units, along with Guidelines on how to use SI unit symbols
How to start a technician fight
When you encounter science technicians in internet discussion groups there are some topics that are hardy perennials. I'll write about others in future entries, but today I'm going to talk about pipettes.
Disposeable (polyethylene) Pasteur pipettes are used in wet labs all over the world. You can buy a pack of 500 unsterilised 3ml ones for about £5 + VAT (UK) from school suppliers. In school labs they are a very good tool for transferring small quantities of liquid from one place to another. The volume markings are surprisingly accurate, and when instructions say "dropwise" it's possible for even the most ham-fisted students to comply.
The question that arouses controversy: should these pipettes be re-used or binned? Re-use might seem the more environmentally-friendly and economic option, but... They take a lot of effort to clean. They have to be filled and emptied manually to rinse them out, and that can take several repetitions (try pipetting some coloured water and then see how many rinses with tap water it takes to get rid of the colour). Putting them in the dishwasher is no good, as water simply does not get inside. Many people overlook one aspect of all this washing up - it takes time, which does cost money (technician wages), and which could be used for doing something else.
How about keeping pipettes for use with specific liquids and solutions? Do you trust students to be careful enough not to use the same pipette for two different bottles, or not to scatter them across the room?
Glass pipettes are an alternative to plastic. One advantage is that they are easier to clean. However, there is a real safety issue. It's very easy students to break them while trying to push the teat in. Their general fragility means that you can get sharp edges easily, which are a danger to students and technicians. And when it comes to disposal they're not recyclable, meaning that they go to the same landfill as plastic pipettes.
We can worry too much about the environmental impact of waste plastic, believe it or not. In a country like the UK with an advanced municipal waste-disposal system, binned pipettes will end up in landfill, not contaminating the general environment.
In conclusion: take the least-worst option, carry on using your plastic pipettes, and bin them.
