Dividing a Fraction by a Fraction – A Japanese Approach (Part One)

As some of you may know, I’m currently in Japan learning about Japanese Lesson Study, with a focus on mathematics. Lesson study itself has nothing specific to do with mathematics, but is a particular way in which the Japanese conduct professional development for their staff. It has been utterly fascinating to watch and learn about, and I’ll be sure to write more about it soon enough. For now though a brief description will have to suffice: Lesson study involves a small group of teachers team planning a lesson over the course of a few weeks (the detail and thought behind the lesson is very impressive) with an agreed focus such as, for example, developing conceptual understanding, or meaningful group participation etc. The lesson is then observed by a (large) number of teachers (sometimes just school staff, sometimes much broader), and then immediately after the lesson a post lesson discussion is held where everyone discusses how to drive the quality of learning forwards. I’m sure that whole process raises some questions, which I’ll try and get to in another post. In this post I want to talk about the strategies I observed for one of the most difficult lessons to teach in school mathematics – the division of fractions by fractions, with a few of my own thoughts thrown in for good measure.

The lesson we observed was part two, with, I assume, at least another two parts to to follow on.

Part one (unseen by me) was effectively a discussion and sort of think tank in which students considered the following problem:

“3/4 of a bucket of paint covers 2/5 of a boat. How much of the boat will a full paint bucket cover?”

The lesson was taught to Grade 6 students (UK Grade 7). During that (unseen) lesson, students derived, with very little to no guidance from the teacher (i can attest a little to this based on the many other lessons i observed which follow a similar structure and strategy) that the way, or, *a* way,  to approach the problem is to divide 2/5 by 3/4 – something they can’t actually do mathematically yet.

This in itself is a marked departure from UK / US strategies. I would never dream of utilising an entire lesson to enable students to effectively just think through a problem and derive what it’s actually asking you to do mathematically – not necessarily because I disagree with it or think it’s a waste of time, but just because I can’t picture it working with many of the classes I’ve taught in the UK due to likely behavioural and perseverance issues.  Regardless, this is not intended as a “we should copy them!” post. I’m just interested in their approach.

One of the ways in which the problem was understood by students was by the use of a tool I’ve personally never used nor seen before, a ‘double number line’. I have no doubt that some of you will have, but this was a new one on me.

The double number line is used as a visual proportional reasoning tool, much like bar modelling or, my preferred proportional reasoning tool highlighted by the late Malcolm Swan in the UK, the four squares method (i’m sure it has a cleverer name somewhere):


The double number line has some advantages (and some disadvantages) over the squares method. Primarily, you can highlight two things at once a bit easier (see in a minute) whereas the squares would, I suppose, require two separate diagrams.

Anyway, the double number line is joint together at zero, and then each proportionately similar element is lined up accordingly. Imagine a proportions x/y table, then make it a diagram basically. So for our paint and boats problem, we’d have a diagram like this:

double number line

The area painted is indicated on the top row, and the paint used is on the bottom. The empty square is what we want to find out. This would not be given to students. Students would come up with this diagram themselves, although they would have used it fairly frequently in similar situations previously. I cannot emphasise enough how much the teacher does not interfere with thinking time, and how long it goes on for (!) we’re talking a very, very long time compared to how I’ve seen it done, or indeed how I’ve done it. A general rule followed is that any hint you give to students immediately narrows their thinking, and that’s bad. I find it hard to disagree, at least in principle. Japanese teachers don’t seem to have the balance here working well enough yet – and I certainly don’t either. Whilst I emphasise thinking time and deep discussion, I like the idea of making them struggle a lot more than I do, but trying to keep them motivated and behaving well is something you cannot take for granted in the UK. Although behaviour was never an issue in the lessons I saw, discussions were so drawn out sometimes that some students were clearly drifting off or losing enthusiasm. In fairness this was always picked up in the post lesson discussions. I suppose the message is that we all know this stuff is hard to do, but worth persistently trying to improve upon.

Anyway, moving on, some students began to see the problem more like this:


So students are thinking about how they get from 3/4 to 1 on the bottom line, in a way that’s easy to them. I should add they can divide and multiply fractions by integers comfortably. Here lies the advantage of this diagram over the four squares. We can show two relationships rather than just one. Incidentally the disadvantage of this method to me is that you can’t show the relationship between the 3/4 and the 2/5 very well.

They then apply the same strategy to the top line and divide 2/5 by 3 (which they can do) and multiply their answer by 4 (which they can also do). So at this point a valid, smart approach to the problem has been thought of, and the problem can be solved. Hurrah! However, there is so much emphasis on thinking through the problem rather than getting the answer, so one method is simply not the end of the matter.

Another student notices that if you divide 3/4 by 3/4 then the answer is 1, because anything divided by itself is always 1. And so they suggest that 2/5 could be divided by 3/4 to obtain the answer, regardless of the fact that they don’t know how to do that mathematically. Fascinating stuff, and I was genuinely surprised at the range of responses time after time, lesson after lesson, when allowing students the freedom to think things through deeply without the interjections of the teacher to willingly or subconsciously shape their thoughts in a particular way.

A third idea was that you could multiply 3/4 by its reciprocal (they know about reciprocals) to get 1, hence you could possibly multiply 2/5 by 4/3. Incidentally no connection was made between dividing by 3/4 and multiplying by 4/3.

All of this was done in lesson 1, and recapped to some extent in the lesson I observed, with the teacher aim of establishing that 2/5 divided by 3/4 was a valid mathematical process to perform to solve the boat problem – to set up lesson 2 to learn how to do it. I’ll get to that in my next post…!

If you want to learn more about Lesson Study as a tool for teacher professional development (I *really* recommend you do, it’s fascinating) then there’s a conference in Nottingham very soon dedicated to it. Here’s the link.


Reflections on 13 years of teaching…

I began my teaching career in 2004, and in two weeks I will be finishing my secondment in schools, effectively ending 13 years of teaching children. It feels appropriate to share a few thoughts and reflections on what I still genuinely feel is one of the most rewarding (and punishing) professions anyone can experience.

The Noble Profession

I did not start teaching because I wanted to help children. Nor did I start teaching because of a nagging dissatisfaction with being a small cog in a big corporate wheel, searching for something more meaningful. I joined because I needed a job, and at the time, teaching was offering a very attractive financial incentive – paying off my student loans over 10 years, and a ‘golden hello’ of about £5000 in my first year after qualifying. It felt like a better idea than continually applying unsuccessfully for graduate IT jobs that had seemingly dissipated after the millennium bug phenomenon.

Today the Government offers similar, but poorly structured incentives to join the profession. A large bursary that effectively salaries your training year (for shortage subjects). However, there are no strings attached. No conditions beyond ‘start training’, and no caveats should you decide to quit during your training, or after your training, or after a term of teaching. In fact, some trainees end up taking what amounts to a pay cut upon graduation.

I didn’t find my training year hard. Everyone always says it’s hard but it doesn’t have to be. It took up a lot of my energy, but the things I was being asked to do didn’t feel difficult, just time consuming. It bothers me that trainees now are often asked to do more than they need to, simply because people seemingly want them to find it as hard as they did. Encouragement seems in short supply.

A love of maths

I was not a fan of maths at all. I wasn’t even a maths teacher. I taught ICT (basically a tour of the Office Suite) which felt like a disappointment after studying programming and mathematics at University (I studied maths because it was valuable, not because I liked it). I was competing with a trainee teacher who had already established themselves in the school we applied to (he was working there), and the school ended up appointing us both because I could offer mathematics as well, despite having no formal training in teaching it. The first 5 years of my teaching career very much had maths as an aside. I was promoted quickly, and became the preposterously pretentiously titled ‘Director of ICT’ after about 4 years. Being promoted quickly was exciting and felt rewarding, but ultimately I became disillusioned, and then I quit.

I was not a good teacher

I don’t look back on my first 5 years of teaching with any particular pride over my style of pedagogy. I got on very well with my students, lessons were relaxed, behaviour was good – after I realised that being a total  asshole with no time for empathy (as instructed) didn’t work well for me at all. But in hindsight, I think people thought I was a good teacher because the students behaved and we were all having a good time. I have no doubt that that’s a key part of doing the job well, and without it you’ll probably struggle, but the way in which I actually taught stuff was pretty poor. I fell foul of many IT lessons that defaulted to ‘research this, present it on a powerpoint’ or ‘get on with your GNVQ coursework’. Worse still, the fact that I was being recognised as an ‘outstanding’ teacher felt counter intuitive. I wanted to get better. To this day I question the notion of what an ‘outstanding’ teacher is. I think a lot of schools still see it as a show. Kids engaged? Tick. Teacher enthused? Tick. Books look ok? Tick. This guy’s great.

Teaching maths felt harder, and more nuanced to me. I liked that, and I always finished a lesson, no matter how well it went, thinking ‘how could I do this better?’.

Working Abroad

As flattered as I should have felt at being promoted quickly, it left me feeling disillusioned and numb about the linearity of a teaching career. I sought a more significantly different edge to my career and applied for jobs that seemed above my station. To my surprise I ended up being an education consultant in the middle east, working with interpreters to help reshape the pedagogy of existing teachers in boys schools. It was a huge culture shock, and the most amazing experience of my life to date. It was here where I started to really invest in my own development. I began reading about the science of teaching, about the science of questioning, understanding, memory, the deeper questions around the purpose of school, and the history of education. Suddenly teaching became so much more interesting to me. It was a kind of awakening, a realisation and an appreciation of the precision, hidden depths and  craft of good teaching. I felt as though I had actively rejected my former teacher self, and the very notion of what was being labelled at the time as ‘outstanding’ (*spit*).I learnt to love mathematics as I worked alongside some of the most enthused and knowledgeable people I’ve had the privalege to meet, who showed me that making sense of mathematics is so much more important than just being able to do it.

I met so many incredible people from different walks of life, all of whom helped reshape my outlook on teaching, and life in general. I saw how valuable education is, and how little we appreciate it back home. I saw the imbalance of privilege – where I could be served in a coffee shop by someone with more qualifications than me, but with the ‘wrong’ colour passport, and I heard of what people go through to be able to give their children access to any kind of education. People who moved away from their families, their countries, just to earn enough to send home to give their children a chance. Children they would see grow up only in snapshots. I thought back to the children I had taught in the UK, utterly oblivious to the enormous liberties afforded to them simply because of where and when they were born. Indeed, I was one of them.

I returned to the UK with, for the first time, a genuine zeal for the profession, which has stayed with me since, and which I try to pass on to trainee teachers embarking on their own journeys.

What we do changes lives. Some will appreciate that, some won’t. Some children would have done just fine without you, some wouldn’t. Some may fail, most won’t. The tragedy of teaching is that you often don’t see just how much impact you had on people. The occasional run-in with a former pupil, or a heart-felt letter at the end of year 11, or a parent telling you how grateful they are for what you’ve done for their child. We cling to those moments, in a time where teaching is harder than it should be. You’ll find those cards, gifts and messages stuffed away in the desks of teachers, or pinned to their departmental noticeboards. Sometimes we need to revisit them to remind us what the hard battle is for.

I’ll miss the buzz of the classroom, the joy of seeing when a concept clicks, the wonder and intrigue of young minds, the eleven year old predicting a room is “about 20 metres tall”. I’ll miss the sixteen year old who is mortified that they just calculated a perimeter as a negative number, the belief reignited in someone who aced a test, the email from a student telling me maths ‘isnt shit with you’, and the nine year old who signed my leaving card on my first school placement “Goodbye Mr Southall, thank you for teaching me, you will always be suspicious.”

Bless them all.