June 10, 2023

Teaching calculations in chemistry

Teaching equation practice in chemistry

One of the key areas of chemistry that students struggle with is calculations. Paper 1 chemistry has so many calculations that need an amalgamation of several niche concepts that students end up selecting which they will tackle or ignore.

Ask any chemistry teacher to list challenges that students face and titrations and reacting masses will be up there. In this article  I outline 2 calculation methods that have helped our students master calculations in chemistry.

FIFA in chemistry calculations 

A few years ago, I joined the ChatPhysics team  and as result engaged more with physics blogs and CPD and one such blog was by Gethyn Jones (co-Author – Cracking Misconceptions in Science). Gethyn shared his use of an acronym FIFA that he used for calculations in his physics lessons (See blog at end of article) 

I rolled out FIFA (Formula, Insert Values, Fine tune, Answer) in our department and it changed the way students tackled calculation questions in physics with most of our foundation students who would leave blanks in their test papers now attempting these questions. Of course it would be silly to assume we just said we are using FIFA and off we went, every student was using it. Instead, implementation required repetition and consistency of approach in every physics classroom as  understandably, formula triangles were so well embedded and as such weaning students and ourselves off them took time and perseverance. 

Thankfully my team were onboard with this change and so we reaped results in record time. 

Once physics was established I then decided to trial using FIFA in chemistry lessons. I had a brilliant chemistry trainee who has seen me model FIFA to my physicists and agreed to trial in his chemistry lessons. To my surprise students engaged with the acronym quite quickly and very soon FIFA became part of our chemistry lessons. 

For those of us that have experience with FIFA, it is particularly useful for multi step calculations where you need to use a formula more than once or multiple formulas. As such FIFA naturally fits in well with the calculations in chemistry. 

Below is how I use FIFA for both moles and relative atomic mass (RAM)  calculations: 

What I love about this method is its logical nature. If we are to prepare students for A Level Chemistry calculations that can sometimes carry 5-10 marks,  logical layout of work is a must. Additionally, sequentially working through problems is highly rewarding and we as chemistry teachers want to show the beauty of maths in chemistry. (Is there anything more satisfying?) 

Table method for reacting masses, empirical formulae and titrations

Another way of  building confidence in multi step calculations in chemistry is using  the Table method. I suspect most teachers would have heard of this method already. I have renamed this Table Method 2.0 because I use either A1 sheets or if my classroom has white table tops students use the table tops. This method only works with well modelled examples as some of the steps can get confusing if students cannot decode the question and identify relevant parts. I usually use this method in a competitive way as a think pair share task where students work in pairs to solve the sum in a timed manner. This is a lot of fun to watch and reduces the misconception that maths is dull. It also supports weaker students to gain confidence. 

As the class teacher I ensure I am circulating during this timed period and asking probing questions to guide students’ thinking which helps those unsure of the steps. An example of a students’ tables during the table method is shown below: 

I guess the question you may all have is why does FIFA not work for reacting masses, empirical formulae and titrations? I honestly haven’t tried to embed FIFA for the above mentioned calculations as the table method is so effective. I guess you could try it but would need a way of getting students  to mentally do mol ratios and Mr which to me is the challenging aspect to the calculations themselves 

With chemistry teaching the imperative is to deliver well explained concepts that are modelled with high clarity to maximise outcomes. Students taught chemistry well develop a love for the subject that is  visible and long lasting. 

If you do try FIFA or the table method in your classrooms please do tag @chatchemistry  on Twitter.

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Thandi is a current Faculty Lead for Science at a school in Surrey. She has previously contributed to Chat Physics and ASE conferences and regularly tweets about teaching and learning strategies in the classroom and STEM. She is interested in developing teachers new to the profession and sharing resources and good practice as well as enrichment opportunities for young people.

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