Acids, bases, resources and more

Bridging the gap

In this issue's Endpoint, Kristy Turner offers some advice on how teachers can help students make a smooth transition from school to university-based education. Suzanne Fergus saw this article on our website and commented:

I enjoyed reading this article and agree with the challenges identified by Kirsty. A lot of first year students struggle with time management. I recently heard one student comment that she relied on hearing about deadlines from her peers so her work was completed very last minute. Sowing the seeds and helping students experience aspects of independent learning and management can only be a good thing.

Acids and bases

In our CPD article, Morag Easson explains how to neutralise student difficulties when learning about acids and bases. Bob Worley added his own suggestions online:

The presence of ions in solutions and solids is indicated by the conductivity of an electric current. This aspect of chemistry is shunted into electrolysis now with no mention of the conductivity of solutions.

In my microchemistry workshops I introduce the CLEAPSS conductivity indicator. It illustrates that pure water conducts an electric current very poorly (no light on the LED) but tap water conducts better as the LED lights up.

Students can insert one tiny crystal of a salt into a puddle of water on a plastic sheet and the LED lights up. We can model this as the water solvating the ions as the crystal breaks up on dissolving.

If you add an indicator to the puddle, the colours around the electrodes change, showing there has to be a chemical reaction for the current to pass. That is the electrolysis.

If I insert an ammeter into the circuit, I can measure the current. I can add an alkali a drop at a time into a puddle of dilute acid and show the value of the current decreasing as more water forms. After a minimum, the end point of the micro-conductimetric titration, the current increases.

In many ways the conductimetric titration is better in educational value than the pH titration with all its mathematical issues illustrated in the article. With a commercial conductivity meter, you can show the effect with precipitation reactions.

I wonder if it is pH that we ought to have got rid of in our syllabus rather than conductivity. The problem is that pH has entered into common parlance.

Teaching resources

What makes a good teaching resource? Stephen Hessey from the Royal Society of Chemistry’s Learn Chemistry team explained how and why resources should be accurate, useful and relevant. For example, making resources available in Word format instead of pdf can make them more useful for teachers. But not everyone agreed. Terran commented:

Requiring a resource to be instructor editable is a bad idea. While we like to think every teacher is as good as we are, they aren’t. Every instructor edit undergoes zero peer review.

Instructors often have pet ways of teaching many concepts. Many of them are pedagogically poor and others are downright wrong. Both leave the students with misconceptions and/or false understandings that will hinder their future learning. Students still trust the textbook like the bible. So if an instructor can integrate their pet way into the bible, the student is doubly doomed.

Al Chemy told us how he was concerned about the quality of resources available from some websites:

Given the importance that we as a society supposedly place on education, it is a surprise that so much of what is done in terms of educational resources is amateurish and of a low quality.

Learn Chemistry is undoubtedly one of the highest quality sources in the world for chemistry, because the resources therein are accurate, tested, well-produced and free. Limitations are that they are often not customisable (ie pdfs not word documents) and don’t have comprehensive curriculum coverage.

Of course, there are official resources that match to courses produced by publishers linked to exam boards but these are increasingly expensive. I work in a school where we can’t afford to buy the textbooks for the new GCSE course, never mind any teacher resource packs.

Then we have sharing sites like TES that have become increasingly commercial in allowing teachers to charge for resources. These are often of dubious quality and tend to fail the key question for any lesson: what are the students going to do?

The transformation to a commercial model begs the question: who is paying for these resources? The answer of course is the teacher themselves out of their own pocket – not something that I feel should be necessary or encouraged. I also note that the number of downloads of many of these pay-for resources is pitiful.

A really good teaching resource allows students to teach themselves. I have been impressed with the RSC’s transition resources from GCSE to A-level and would love to see that electronic platform developed properly to allow teachers to set tasks and see what their students are doing. Chemistry as a subject is miles behind mathematics in this respect and there is a major opportunity to improve student learning and reduce teacher workload at the same time.

However, Patricia Coffey disagreed:

Being relatively new to teaching after leaving the pharmaceutical world I have found these resource providers invaluable even if I do have to spend time sifting through to find the right resource. I often change these resources to suit my own style of teaching but it still saves me time not having to start from scratch.

I would also have to say I think the new payment model is good. Any of the resources I have paid for since this has been introduced have always been excellent. So parting with £1–2 knowing that I am going to get a high quality resource is worth it in my opinion.

As I teach iGCSE chemistry and International Baccalaureate chemistry I prefer when the resources are specific to these courses. However, there is not always as much for these as there is for GCSE and A-level so I again adapt what is available. I have recently began thinking about sharing my own resources on these platforms; I’m just not sure if I am that confident yet!