Making Your Own Sense

Reflections on maths, learning and maths learning support, by David K Butler

Author: davidkeithbutler

  • One Hundred Factorial – the puzzle and the event

    The weekly puzzle session that I run at the University of Adelaide is called One Hundred Factorial. In the middle of the night, I suddenly realised that I have never written about why it is called One Hundred Factorial, and so here is the story.

    The very beginning

    Once upon a time I was a PhD student in the School of Mathematical Sciences at the University of Adelaide. Sometime during the third year of my PhD program (2007), I was asked to give a talk to the first year undergraduate students as part of an evening event where the goal was to hopefully convince them to keep studying maths at a higher level next year. I titled my talk “How to Tell If You Are a Mathematician”. I don’t remember any of the things I spoke about, except for one thing. Before I started talking, I put a puzzle up on the document camera. I did not mention the puzzle in any way or look at the screen at all. I just did my little talk as if it wasn’t there. But right at the end of my talk I said this:

    The final and truest way to tell that you are a mathematician is that you haven’t been listening to any of what I just said, and instead have been trying to solve this puzzle.

    Cue guilty looks and nervous laughter from all of the academic staff in the audience, which successfully proved my point. Anyway it worked. Several students came up to me to talk about the puzzle, and I was able to direct them to lecturers who could talk to them about their study options. Yay for puzzles, right?!

    This was the puzzle I used so neatly to make my point about the mathematician’s mind:

    The number 100! (pronounced “one hundred factorial”) is the number you get when you multiply all the whole numbers from 1 to 100.
    That is, 100! = 1×2×3×…×99×100.
    When this number is calculated and written out in full, how many zeros are on the end?

    I don’t remember where I got the puzzle from, but it is a pretty famous one that’s been around for some time. I actually hadn’t even thought through a solution at the time either. I just knew that it mentioned a concept that had been in the first year lectures recently.

    The puzzle sessions begin

    The other thing that happened that night was that a group of students and staff stood at the blackboard in the School of Maths tea room to nut out a solution to the 100! puzzle. I can’t even remember if we finished it or not, but we did decide that we should get together regularly to solve puzzles together, and a weekly puzzle session was born. At the first session, we started with the 100! problem again, and an extension of it, which is to find out what the last digit is before all those zeros start. Then as the weeks went on, we would do puzzles that I would find and bring to the sessions.

    When I finished my PhD in mid-2008 and took up the job in the Maths Learning Centre, I took my little puzzle session with me, and was able to invite more students to come along, and it slowly morphed into a student event more than a staff event, which really pleased me. In fact, a regular at these puzzle sessions for years was that first student who had come up to me after my talk at the first-year event, and he eventually became one of my tutors at the MLC.

    The name of the event

    Over the years the puzzle session has had many names. We started out calling ourselves “People with Problems”, and then simply “Puzzle Club”. For a while it was called “The Hmm… Sessions” after the sound we made very often while thinking about puzzles. Indeed, there is a reference to the Hmm Sessions inside this very blog. But in 2012 after the website where I was hosting our online discussion was decommissioned, I decided it was time to change the name. I was also starting to think about moving the sessions out of the MLC itself and into a public space, and to match with this move I wanted a new name. I thought long and hard, and decided to name it after the first puzzle we ever did, the puzzle that first inspired staff and students to talk and think about maths together, the puzzle that helped students decide they really were mathematicians after all.

    The legacy

    So the regular puzzle session of the MLC became One Hundred Factorial at the end of 2012, and here we are in 2020 still going, so that now it’s been One Hundred Factorial longer than it’s been any other name. It’s been my testing-ground for new puzzles and games and teaching ideas, a place where I have made friends and welcomed people from around the country and the world. And it has become a glowing island of mathematical play in the middle of the stressful university life, and indeed the middle of a stressful life generally. In recent weeks it is a glowing island of community in a world of pandemic-induced isolation.

    One Hundred Factorial reminds us that there is always something joyful to think about if you are looking for it, and that it’s okay to pause and ignore your responsibilities for a while to think about it, and that doing this with people is a source of shared joy. I hope the puzzle and the event can keep reminding us of that for a long time yet.

  • The Operation Tower

    I don’t like BODMAS/BEDMAS/PEMDAS/GEMS/GEMA and all of the variations on this theme. I much prefer to use something else, which I have this week decided to call “The Operation Tower”.

    A diagram of the Operation Tower. Three stacked boxes with a dotted area on the left hand side. The bottom box has a plus and a minus. The middle box has a times and divide. The top box has an exponent carat and a root symbol. The dotted area on the side contains two shapes of brackets and a horizontal bar.

    You can read the rest of this blog post, and the other posts in the series across the years, in PDF form here. 

    The titles of the five blog posts are:

    • The reorder of operations
    • (Holding it together)
    • The Operation Tower
    • Replacing
    • Sticky operations

  • Digit Disguises

    This blog post is about a game I invented this week, and the game is AWESOME, if I do say myself.

  • Context fatigue

    Context fatigue is a particular kind of mental exhaustion that happens after having to make sense of multiple different contexts that maths/statistics is embedded in. I feel it regularly, but I feel it most strongly when I have spent a day helping medical students critically analyse the statistics presented in published journal articles.

    The problem with maths in context is that the contexts themselves require understanding of their own in order for the maths to make sense. This is nowhere more true than in statistics, where you have to use your understanding of whether you expect the relationship to exist, what direction you expect it to be, and whether you think this is a good or bad thing. The classic one in my head is an old first year statistics assignment where they used linear regression to investigate the relationship between manatee deaths and powerboat registrations in each month in some southern coastal American city. You have to know what a manatee is, what it means to register a powerboat, and why those things might possibly be connected in order for the statistical analysis you’re asked to do to make sense, not least because at least one part of the question will ask you to interpret what it means. When helping students read published articles recently, I’ve had to find out what’s been done to the participants in the study, how things have been measures, what kind of measurements those are, why they’ve been measured that way, and all sorts of little details to decide how to interpret the numbers and graphs that are presented.

    Even ordinary everyday word problems are a minefield. Across two recent assignments, some financial maths students had to cope with album sales for AC/DC, flooding of the land a factory is built on including insurance, bull and bear markets, machines in a mining operation, committees with various named positions, road testing electric cars, contraband being smuggled in shipping containers. This is a lot of context that has to be made sense of before you can get a handle on the maths, and there is nothing in the question itself to tell you what any of this context means if you don’t already know. Even if you are already familiar with the context, you actually have to suspend some of your understanding in order to do the maths problem, because it’s much simpler than the actual situation any of the questions are talking about.

    All of this interpreting is exhausting stuff! It just tires you out if you have to even a moderate amount all at once. You just feel like you don’t have any more energy to deal with any more today. That feeling there is context fatigue. Yesterday the first year maths students were doing related rates and every question was a new context with little nuances created by the context that had to be dealt with. Those poor students were exhausted after just one problem, letalone three or four.

    As teachers, we need to realise that as the people writing the assignment questions, or at least people who have dealt with them before, we are much more aware of the details and nuances of the context than the students are, so we don’t have to work so hard to make sense of them. Not only that but we’re usually simply more experienced in both life and language than most of our students so it’s easier for us. Imagine the context fatigue you would get reading ten research papers in an unfamiliar area in one day (I feel this in real life regularly). That’s the sort of context fatigue your students have just from your assignment questions. Cut them a little slack, and make sure there is adequate time to process the context with appropriate rest time between context-interpretation. Also it wouldn’t be the worst thing to explicitly teach them strategies for making sense of context, such as ignoring the goal, and finding out about what some of the words mean. Strategies can make the work less intimidating, especially in the face of knowing how tiring it is already!

    PS: If you’re in charge of tutors in a drop-in support centre, especially one that deals with statistics, please be kind. Context fatigue is real and tends to wear us down some days!

  • The curse of listening

    I am often saying how important it is to listen to students, and that I am fascinated by student thoughts and feelings. When students say I am a good teacher my usual response is to say it’s because I have spent the last eleven years in a situation where I get to listen to lots of students.

    But there is an important thing I almost never talk about, which is that sometimes listening is actually awful. I can think of not many more debilitating curses to lay upon people than to wish them the ability to listen.

    Because listening is exhausting.

    Because I am listening to students, I know an explanation doesn’t work, so I have to come up with new ones, usually on the fly. Because I am listening to student thinking, I come across new ways to think about all sorts of things that I had never considered before, which I then have to process. Because I am listening, I am faced with people’s feelings and stories, which I have to process emotionally. Because I am listening, I can easily become fascinated with new ideas and problems which take up my mind. Because I am listening, I hear things that need changing in teaching methods or university systems, and either try to work to change them or worry that I can’t. In short, because I am listening I am constantly processing information and emotions both in the moment and later on. It’s exhausting.

    I don’t always cope well with it. In person with students I can just deal with who is in front of me and it’s ok, though there are times I need a break and just walk away for a few minutes. Unfortunately when I’m apart from the students, I can’t leave my brain behind and I carry with me the swirling thoughts in my head all day long caused by the listening to students. One way I have to cope with this is to talk with people about those thoughts, in person or on Twitter. But I actually can’t talk about all of them, so I have to choose one thing to think about and ignore everything else. There are times I have to say to students or my tutoring staff that actually no I can’t think about that right now, which is really really hard. And there are times I can manage to do an activity like origami or folding or watching tv to turn off my brain for a while to give it some rest. Still the call to listen is back again soon enough.

    This isn’t a whinge session to get sympathy, it’s a warning. Be warned that if you choose to listen, you too will have to find ways to ignore some things, to find moments of brain-calm, and to find ways to process the thoughts you do choose to entertain.

    Was my aim to scare you off? Certainly not! I wouldn’t ever give up listening and sacrifice the pleasure and learning I get from it, or the benefit it has for students. The blessing far outweighs the curse.

    Just be prepared, ok?

  • The importance of names

    Three years ago, my university’s Student Engagement Community of Practice collectively wrote a series of blog posts about various aspects of student engagement. I thought I would reproduce my blog post here, since it is still as relevant today as then.

    There is a lot that staff can do to engage students in the university community and in their learning, and a lot of these things have to do with the staff being engaged with the students. One way that any staff member can show their own level of engagement with the students is to learn the students’ names.

    Names are important. Your name is a part of your identity, and not just because it is what you call yourself. Your name may tie you to the culture or the land of your ancestors, or it may speak of your special connection to those you love. You may prefer to be called by a different name than your official one because your chosen name is more meaningful to you. What all of these have in common is that your name is an important part of your identity.

    For myself, my name is David, and I don’t like to be called Dave. I grew up in a community with several Davids and other people were called Dave, so being David kept my identity separate to theirs. Yet many people give me no choice and call me Dave without asking for my permission, despite me introducing myself as David. I find it intensely rude that someone would choose to call me by a different name than the one I introduce myself. On top of this, I am a twin, which means as a child I was forever being called by the wrong name entirely. We are not identical twins, and yet this still happened, because we were introduced as PaulandDavid, without an attempt to give us a separate identity. The fact that I was called Paul, or “one of the twins”, meant that I had no identity of my own separate to my brother. Being called David means that I have an identity of my own and this is important to me.

    For many students, these and worse are their daily lives. Imagine a student who no-one at university knows their name. They have no identity at university, can feel very alone and can quickly disengage. Yet according to “The First Year Experience in Australian Universities” by Baik, Naylor and Arkoudis  , only 60% of first year students are confident that a member of staff knows their name.

    Not having your name known at all is one thing, but being called by the wrong name can be worse. An international student has to deal constantly with being different to other students, and in the community at large has to deal with a lot of everyday racism. To have your name declared “difficult to pronounce”, or to have it declared as not possible to remember, is just another one of these everyday racist events. The person doing so may not be meaning to be racist, but it adds up to the students’ feeling of not belonging, to their feeling that they themselves are not worth remembering. Similar to me and my twin brother (only worse), they may have the feeling that others believe all international students are the same, so why remember them separately. In “Teachers, please learn our names!: racial microagression and the K-12 classroom” by Rita Kholi and Daniel G Solórzano , there are many examples of the hurt that such treatment of student names can have.

    So what can we do to learn our students’ names? Members of the Community of Practice suggested several strategies.

    One idea is to spend time talking to them and ask them what they would like to be called. You can’t learn their names unless you find out what they are! Be visible in your effort to pronounce it correctly, be adamant that you want to call them by the name they ask to be called. If you get multiple chances to talk to them one-on-one, ask their name again if you can’t remember and try to use it as you talk to them.

    Another idea is to print out photos of your students and to practice remembering their names. If you don’t have access to their photos, then it should not be hard to find someone nearby who can. (Though of course it would be excellent if there were a simple system whereby anyone teaching a class — including sessional staff — could get photos of their students!) Even if you can’t get their photos, simply working your way down the roll and remembering how to pronounce those names, or what the students’ actual preferred names are, is good exercise. The students are likely to appreciate the effort you put in here, even if they can’t know how much time you did put in!

    You may have your own ideas on how we can make sure we know students’ names. I’d encourage you to share them in the comments, along with any stories of how it made a difference to student engagement.

    I would like to work in a university where 100% of the students are confident that someone knows their name. We have hundreds (possibly thousands) of staff in contact with students on a regular basis. If each of us only learns a tutorial-worth of names, then we can surely meet that goal easily!

  • Struggling students are exploring too

    I firmly believe that all students deserve to play with mathematical ideas, and that extension is not just for the fast or “gifted” students. I also believe that you don’t necessarily need specially designed extension activities to do exploration – a simple “what if” question can easily launch a standard textbook exercise into an exploration.

    This is lovely, but one problem is those students who on the face of it don’t want to play. The majority of students I work with in the MLC are not studying maths for maths’s sake, but because it is a required part of their wider degree. That is, I am helping students who are studying maths for engineering, or calculations for nursing or statistics for psychology. A lot of these students just want to be told what to do and get the maths over and done and don’t like “wasting” time playing with the ideas.

    Or so I thought. I have realised recently that actually they do like playing with the ideas. I just couldn’t see that this was what they were asking for.

    One of the questions I like to use to play with maths is “what if?” To ask it requires the asker to notice a feature they think might be different, and wonder what would happen if it was, and so investigate how this feature interacts with the other features of the situation. This investigation of how ideas interact is exactly what mathematics is, to me. I am very very used to doing it at extracurricular activities like One Hundred Factorial, and it’s easy to do with students who are doing very well with their maths and have the breathing space to wonder about this stuff because they’ve finished their work. For students working on an assignment they are really struggling with that they wonder about the usefulness of for their degree and which is due in the next 24 hours, it’s not so easy.

    Only maybe it’s a little easier than I thought, because I started to notice that the students were already asking questions about the connections between things.

    A very common question students ask around exam time is “What would you do if the question was like this …?” as they suggest a change in a small detail that makes it more similar to the past exam question they have at hand. I used to get really annoyed at this sort of question, but then I realised that in order to ask this question they had already noticed that the two problems were similar in most respects and different in this one. Sure, they may be motivated by a belief that success in maths is about a big list of slightly different problems and remembering ways to deal with each, but on the other hand they have noticed a relationship and are trying to exploit it, This is a mathematical kind of thought, to look for similarities and differences and relationships, and we can hang on tight to it and actually learn something!

    Another kind of question students ask is “Why is this here in this course?”. I used to get annoyed at the whinging tone of voice here, but then I realised that a student is begging for a connection between this and the rest of what they are studying, and connections is precisely what understanding maths is all about. I can respond to it by saying that yes I am also confused about the curriculum writer’s logic for including it, but then we can search out connections together to see if we can find them.

    A third kind of question is the one where the student looks at the lecture notes or solutions and asks “How did they know to do this?”. Sure, it’s usually motivated by wanting to be able to successfully do it in their own exam in restricted time, but on the other hand it does recognise that there ought to be reasoning involved in that decision, as opposed to just guessing. This expectation of reasoning is the beginning of believing that they themselves could reason it out too.

    My second-last kind of question is “Why is this wrong?” as the student points to the big red cross on their MapleTA problem on the screen. Sure they just want to make it all better so they can submit the damn thing. But they are also recognising that there must be a reason why it’s wrong, and so are looking for meaning. These students are often ripe for the experience of looking at the information and how it’s related to what they’ve entered, thus doing exploration. They are also usually ready to try various different ways of entering the result, or different strategies of getting a right answer to see where the edges of the idea are.

    The final kind of question I want to mention isn’t even a question, it’s an exclamation of “It doesn’t make sense!” Even this is telling me that the student thinks it ought to make sense. They are crying out to do something to make sense of it. Often they describe being almost there and needing something to push them over into understanding. This student is ready to explore the edges of the understanding they do have to see where the nonsensical stuff can fit, or where their ideas need some tweaking to fit together better.

    It is very helpful to me as a one-on-one or small group teacher, or even a lecturer with a big room of students in question time, to be able to see the questions struggling students are asking as cries for sense-making exploration. It doesn’t matter that they are struggling or don’t understand things. Indeed, being in a situation of not knowing is exactly what we are doing for the fast students when we give them extension activities, so why is the everyday maths the slower students are not understanding any different? In my experience students like being treated as if they are behaving like mathematicians when they have these struggling sorts of questions. And it was so much easier to treat them that way after I realised they are behaving like mathematicians when they have these kinds of questions.

  • Trying maths live on Twitter

    Once upon a time, I decided I would be vulnerable on Twitter. As part of that, when someone posted a puzzle that I was interested in, I decided that I would not wait until I had a complete answer to a problem before I responded, but instead I would tweet out my partial thinking. If there were mistakes I would leave them there and respond with how I resolved them, rather than deleting them and removing the evidence that I had made a mistake. I wanted the whole process of solving problems to be out there in plain sight for everyone to see.

    One reason I wanted to do this was because too often we give the impression that maths is all so slick and easy, when really it is actually messy and hard. This issue is exacerbated by the nature of puzzles, which often have clever simple solutions, and when people share only that, we give this impression that maths is done by some sort of divine inspiration of the clever trick. I wanted my responses to problems to show the honest process of muddling through things, and getting them wrong, and only seeing the clever idea after I’ve done it the unclever way, and even if a clever way did occur to me, what it was that made me think of it.

    Over time, this has grown into me doing epically long tweet threads where I live-tweet my whole solution process, including all the extra bits I ask myself that are sideways from or beyond the original goal of the problem. I have to say I really really love doing this. I love puzzles and learning new things, and it’s nice to do it and count it as part of my job. I also get to have a record of the whole process for posterity to look back on. Even in the moment, it’s very interesting to have to force myself to really slow down and be aware of my own thought processes enough to tweet them as I go. In my daily work I have to help other people to think, so the sort of self-awareness that this livetweeting of my thought process brings is very useful to me, not to mention fascinating.

    In the beginning, I had some trouble with people seeing my rhetorical questions as cries for help and jumping in to try to tell me what to do. I also had people tell me off for not presenting the most elegant solution, saying “Wouldn’t this be easier?” Every so often I still get that happening, but it’s rarer now that I have started to become known for this sort of thing. I am extremely grateful that a few people seem to really love it when I do this, especially John Rowe , who by rights could be really annoyed at me filling up his notifications with hundreds of tweets with a high frequency of “hmm”.

    I plan to continue to do this, and so if you want to keep an eye out for it, then I’ll happily let you come watch. From this point forward I will use the hashtag #trymathslive  when I first begin one of these live problem-solving sessions, so I can find them later and you can see when I’m about to do it. (I had a lot of trouble looking for these tweet threads, until I remembered that a word I use often when I am doing this is “try” and I searched for my own handle and “try”. In fact, that’s the inspiration for the hashtag I plan to use.)

    Note that I am actually happy for people to join in with me – it doesn’t have to be a solitary activity. I would prefer it if you also didn’t know the solution to the problem at the point when you joined in, but were also being authentic in your sharing of your actual half-formed thoughts. I definitely don’t want people telling me their pre-existing answers or trying to push me in certain directions. If you feel like you must “help” then, asking me why I did something, or what things I am noticing about some aspect of the problem or my own solution are useful ways to help me push my own thinking along whatever path it is going rather than making my thinking conform to someone else’s. I will attempt to do the same for you.

    To finish off, here are a LOT of these live trying maths sessions.

    (Note: You can see copies all these tweet threads in a PDF document here. )

  • Tutorials for an intro Arts course: Story makes sense of number

    Sometime in the past, I was approached by academics in the Faculty of Arts to discuss the numeracy skills of the students in their faculty. They wanted to discuss how they might include numeracy skills in some of their courses across all the degrees they teach. It was a lot bigger than the MLC could reasonably do, but I said I would certainly be able to do a small thing in a few courses, and certainly help their students in the MLC itself when they came to talk.

    Then in January 2019, almost out of the blue, I was sitting down at a meeting with the Faculty of Arts Associate Dean Learning & Teaching, and the course coordinator for their core first year course called “The Enquiring Mind”. We were talking about how I might run a workshop for their students to introduce the importance to numerical skills for Arts students. We agreed on Week 4 of semester, and then I walked away into the Summer School exam period and O’Week and the crazy beginning-of-semester rush, with ideas percolating in the back of my mind for what I could possibly do in an hour.

    You can read the rest of this blog post in PDF form here. 

    Also, I thought I would collect together the resources if you want a closer look at them.

    Thanks for reading.

  • Playing SET

    Amie Albrecht recently posted a most wonderful blog post about SET,  and it reminded me there were some SET-related things I should post too.

    You can read the two posts in this series in PDF form here. 

    The titles of the two posts are:

    • Teaching people to play SET on the fly
    • Team SET

    Resource linked in the blog posts: