Frost diagrams chart the energies of an element’s oxidation states in solution. They’re good: a trained electrochemist can use them to deduce several sophisticated chemical features of the system at a glance.

I teach Frost diagrams to my first year as part of their course on transition metals. By the end of the course, they should be able to construct and interpret a Frost diagram.

Unfortunately for everyone involved, this means I should be able to do that, too.

An Awkward Mistake

In my first year teaching this topic, I messed up. I plotted a Frost diagram exactly the wrong way up by missing a minus sign somewhere. It surprises me how often a minor error in Inorganic reasoning leads to exactly the wrong answer rather than a nearly-right one. My error came at the end of my lecture, and I didn’t have the headspace to see where I’d gone wrong. 

So the following morning I made a short (<10min) video where I got it right. This was perfectly correct, even if it was slightly imperfectly recorded (I still cringe a little listening to it). I circulated it to students and forgot about it.

A Nice Opportunity 

A year rolled round, and I reviewed my notes for the lecture course. I was looking for a chance to turn didactic teaching into something more active (I’m trying to do this with one lecture from every course each year). Frost diagrams seemed like a good choice: the topic is fairly self-contained; they require a mastery of a (fiddly) process; and I’ve got a serviceable 10min video ready to go.

Teaching Preparation

I collated reduction potentials for species of six elements in solution and printed these together with six blank sets of Frost axes. Intending for students to work in small groups, I made copies assuming 100% attendance and groups of 5 people. I sent round a link to the video, made repeated mention of the pre-lecture viewing required for the lecture session.

Teaching Delivery

I didn’t Panopto-record the session, as I hoped to make quite heavy use of student input.

Using MentiMeter for anonymity, I asked students about their preparation. Most students had watched the video, and nearly all groups contained someone who had. I opened a MentiMeter comments page so that I could respond to problems if students wanted to raise anything (which wasn’t used too much), and went through the first one as a demonstration.

Every few minutes, I asked for a group to volunteer their Frost diagram for public marking on the visualiser. I felt a bit sorry for the first group, who made all the errors I remember making myself at their stage (most prominently: treating each cell potential as being relative to the zero state rather than the step from the adjacent state). They took the criticism well, and clearly improved for it. I tried to take diagrams from different groups, and the quality through the session clearly improved.

A short exit poll suggested that the flipping was challenging but useful; respondents indicated that I should keep it in my course next year.

Reflections on Teaching

I felt very nervous preparing for this – the whole event relied very heavily upon student attitudes. If they hadn’t prepared or hadn’t been so willing to share their work, the whole session would have been terrible.

In the event, these fears were without merit. The students got stuck in and did some great learning. The room was bubbling with authentic Chemistry conversations. I got to give feedback on real pieces of student work. It was really enjoyable teaching.

I wonder how the small group dynamic affected the learning of individuals. It might be that some groups had members who didn’t get involved. I feel confident that the group feedback was useful for everyone, but ultimately have no way of knowing whether this is true (not unlike a didactic lecture).

From a teaching anxiety perspective, I note that flipping this teaching has removed any risk of me plotting a diagram the wrong way up; commenting constructively on students’ upside-down diagrams was actually a really nice moment in the power dynamic because I could remind them that I had made my video after making exactly this mistake myself.

Reflections on Flipping

There must be topics which suit flipping particularly well; I suspect that this is one of them. I think that this is because there is a clear algorithm behind constructing the diagram which responds in a really detailed way to the specifics of the data. The interpretation of the diagrams is quite satisfying once you ‘get it’, and is separate to the construction process. This means that students who got the diagram wrong (often through some minor arithmetical error) can be brought back into the conversation at the end.

This was the most unambiguously successful piece of teaching innovation in my year. I fretted over it beforehand, but now I can’t imagine reverting to traditional lectures for this topic.