The Language That We Use

I recently engaged in a spirited discussion prompted by Patrick Honner (@mrhonner) on twitter and on his blog. The original post that started this whole discussion can be found here and it is well worth your time. Engaging comments there an on the twitters and a friendly suggestion by Patrick himself has me writing here, thinking out loud.  To set the stage for this post, an image from Patrick’s post is important.

Screen Shot 2016-07-31 at 8.34.15 PM

A quick glance at this certainly suggests that these are congruent figures until you look more carefully at how the question is worded. This is a pretty classic example of the kind of question that makes students think that test writers are gaming the system to catch them in a mistake. We are looking at two figures that are equivalent to each other. A rigid transformation maps one onto the other. However, that mapping does not map them in the order suggested. A classic mistake that I lost points for as a student and one that, sadly, I admit that I have probably deducted points for when grading. The debate on the blog and on twitter raised some really challenging questions about our goals with this type of specificity. Yes, mathematics is a precise language and precision is a powerful habit to try to help develop. However, I keep thinking about my fun Geometry class from last year. When we were discussing how to determine whether  a triangle with given side lengths was acute, right, or obtuse we worked out a strategy where we assumed that the Pythagorean Theorem would hold and we decided what the consequence was when it did not. This led to my students saying things like this; “If the hypotenuse is bigger than we thought it would be, then the triangle is obtuse.” Now, I know that the largest side of an obtuse triangle is not called the hypotenuse. When pressed on the issue I suspect that almost all of my students knew this as well. Optimistically, I want to say that they know this as well, but is is early August… My concern here is that I was letting them down by letting them be a bit lazy with their language. What I did at the time was to gently remind them that hypotenuse was not the best word to use there but I understood what they meant when they said it. Should I have made a bigger deal about this at the time? Was I being understanding and flexible? Was I being undisciplined and imprecise? I suspect that there is a decent amount of both of these in my actions and I have to admit that I did not think too deeply about it at the time. In the wake of the conversation that Patrick moderated, I am thinking deeply about it. It is also early August (again, I not this) and it is the time of year that my brain reflexively starts dwelling on teaching again. I am also thinking about a distinction that I got dinged for as a student but this time it is one that I do not ding my students for. I remember losing points in proofs if I jumped from saying that if two segments were each the same length then they are congruent. This is, obviously, true but I was expected to take a pit stop by making two statements along the way instead of jumping straight to congruence. I know that equivalence of measure and congruence of segments (or the same argument with angles) are slightly different meanings. A nice explanation is here at the Math Forum. But I feel pretty strongly that my 9th and 10th grade Geometry students are not tuned in to the subtle differences and I think I am prepared to defend my point of view that they do not need to be. I want my students to be able to think out loud and I DO want them to be careful and precise in their use of language but I do not want them to think that this is some sort of ‘gotcha’ game where I am looking for mistakes and looking for reasons to penalize them.

I am thankful to Patrick for getting this conversation started and for gently nudging me to try and work out my thoughts more thoroughly on this issue. I am interested in hearing from other teachers – particularly Geometry teachers – on how they try to navigate these conversations. How precise should our high school students, especially freshmen and sophomores, be when discussing these issues?

As always, feel free to jump in on the comments section or reach out to me through twitter where I am @mrdardy


This is also posted over at my new site and this may be the last one that I cross post. Please visit me over at



Brief Thoughts About Classroom Closing Strategies

I am still processing the keynote speech that Tracy Zager (@TracyZager) gave at TMC16 and I hope to write a coherent blog post about it soon. One thought that is on my mind because of her is that I need to make a serious commitment to thinking more deeply about how my classes end each day. FAR too often they end with me, or a student, noticing that time is up (we do not have beginning or ending bells for our classes) and everybody packing up quickly and scurrying off to their next class. This has to stop. It is not fair to my students AND it undermines any habits of thoughtful reflection that I claim to be important for me and for my students.

At my last school I had an alarm clock app on my laptop that was relatively easy to manage. I programmed it every morning to sound with 3 minutes left in class. I had it linked to a portion of Steve Reich’s Music for 18 Musicians on my iTunes library. What happened at this point was that the music faded in and increased in volume for about 30 seconds. This was our cue to start wrapping up class. My students got in the habit of using this time to slowly pack up their page while we tried to have a conversation about what went on in class that day. When I changed schools I changed laptops and I did not find a similarly friendly app. I also was not thrilled with how those conversations went so I sort of abandoned this idea. Looking back, I am pretty disappointed in myself about this. Whether or not I can find an appropriate timer app (I could, of course, just use something as direct as a kitchen timer) I certainly did not need to abandon this idea. We have been having conversations at our school about our schedule and about the busyness of each day for our students. Our classes are in three different building on our campus and there are many times during the day where the five minute passing time between classes is a stretch for some of our students. If they simply dash from one class to the next with no structured opportunity to pause and reflect, then we teachers should not be surprised when there is less than ideal recall about recent conversations and activities in class. I do not want to obsess about each minute we spend together and get defensive about the idea that ‘class time’ ends before the actual end of the scheduled class. Looking back at the habit I tried to instill at my last school, I think I was coming from a good place. I often framed these two to three minute chats just in the light of ‘What do we know now that we did not know 40 minutes ago?’ and I suspect that this is a decent place to start. However, as with most classroom practices, if I am not diligent and thoughtful about its implementation, I suspect that students will simply see my class as one that ‘ends’ three minutes sooner than it is scheduled for. I also think that they would be largely appreciative of this extra time to breathe, to dash to the bathroom, or to simply stroll to their next class at a more leisurely pace. Honestly, this little advantage in and of itself would not be a bad thing. But I have larger goals than that. I want my students to start to get in the habit of reflecting on our time spent together, to think about how we have grown as a group in our time together, to pause and reflect on an important problem we discussed, a surprising result we found, or a challenge that still lies before us. If I have any real hope of this happening, I need to be a disciplined and structured role model for this habit and, I think I need to be transparent about this. I want to discuss this as a goal at the beginning of the year and I want to refer back to this conversation. Recently I shared a document I created called How to Succeed in Geometry. You can find it here. It is a draft in progress and I intend to create similar docs for my other courses. I need to add in some more description at the beginning about how we will conduct discussions in class (thanks to the great TMC16 morning session run by Matt Baker (@stoodle) and Chris Luzniak (@pispeak)), how we will try to end our time together on most days, and how we are going to commit to paying attention to each other and not just to what old Mr. Dardy has to say on any given day.

Please help me flesh out and improve my ideas about classroom closing strategies by sharing your questions, comments, stories of success in this area either here in the comments or over on the twitters where I am @mrdardy



Note: This is cross posted from my new site. You can find me at

Soon, I will only post from there. I hope you’ll migrate over there with me.

TMC Reflections, Part Three

In this post I want to concentrate on a couple of the afternoon sessions I attended. The TMC program (you can find it here) was filled with so many interesting opportunities that I kind of agonized over some of the choices. One that I knew I would attend was the session run by Danielle Racer (@0mod3) discussing her experiences in implementing an Exeter-style problem based approach to Geometry this past year. Danielle and one of her colleagues (Miriam Singer who is @MSinger216) came back from the Exeter summer math program (it is called the Ajna Greer Conference and if you have never been, I suggest that you try to change that!) all fired up and ready to reinvent their Honors Geometry course. Danielle spoke eloquently about their experiences and shared out some important resources. We had a great conversation in the session about the benefits and struggles of problem based curriculum. This conversation tied in to another session I saw as well as some thoughts and conversations I have been having for years. First, the afternoon session that I think linked in here. Chris Robinson (@Isomorphic2CRob) and Jonathan Osters (@callmejosters) are colleagues from the Blake School in Minneapolis.  Chris and Jonathan spoke about a shift in their assessment policy that centered around skills based quizzes using and SBG model and tests that were more open to novel problem solving. I am simplifying a bit here for the sake of making sense of my own thoughts. I thought that their presentation was thoughtful and it generated great conversation in the room. Perhaps we (especially I) spoke out more than Chris and Jonathan anticipated and we ran out of time. Another sign of a good presentation, I would say. When there is more enthusiasm and participation than you thought you’d get, it probably means that you are tapping in to important conversations AND you have created a space that feels safe and open.

These two sessions had me thinking about some important conversations we have been having at our school and I am totally interested in hearing any feedback. The first conversation I remembered was with a student who had transferred to our school as a senior and was in my AP Calculus AB class. She was complaining about my homework assignments which were a mix of some text problems and some problem sets I wrote. She said in class, ‘You seem to think that AP means All Problems.’ A little probing revealed that she saw a difference between exercises and problems. A brief, but meaningful, description I remember reading is that when you know what to do when you read the assignment then it is an exercise. If you read it and you don’t know what to do, then it is a problem (in more meanings than one, I’d say). The next conversation I recalled was with a colleague who has now retired from math teaching. We were talking about homework and the struggles with having students persevere through challenging assignments. He also used this language making distinctions between exercises and problems and he suggested that HW assignments should have exercises and problems should be discussed in class when everyone was working together. He felt that the struggle and frustration of problems when you are on your own would be discouraging to too many students and would likely lead to less effort toward completion on HW. A similar conversation came up with another former colleague who was frustrated with some of the problem sets I had written for our Geometry course. She did not want to send her kids home with HW that they would not be able to complete successfully. I recognized that this was coming from a fundamentally good place. She did not want her students to feel frustrated and unsuccessful. However, I firmly believe that real growth, real learning, and real satisfaction are all related to overcoming obstacles. I have witnessed this recently with my Lil’ Dardy who just became a full fledged bike rider this summer. I heard it from my boy, my not so Lil’ Dardy, who made the following observation recently, ‘You know, I find that I like video games much better if they are hard at first. Why do you think that is, dad?’

I know that we can anecdote each other to death on these issues and I also know that there is not ONE RIGHT WAY to do this. But I am in the process of trying to make coherent sense out of my inherent biases toward problem based learning. I want to have deep and meaningful conversations with students, with their parents, with my colleagues, and with my administration about how to approach this balance and about what a math class should look like and feel like in our school. While I have been writing this I was also engaging in a meaningful twitter chat about some of this with the incomparable Lisa Henry (@lmhenry9) and with one of my new favorite people Joel Bezaire (@joelbezaire) so I know I am not the only one struggling with these questions. Please hit me up on twitter (@mrdardy) or start a raging conversation in my comments section sharing your successes/failures/theories about how to strike a balance between exercises and problems between challenging students while making them feel safe and successful and between running your own classroom with your own standard and fitting in with a team at your school. These are all big questions and I wrestle with them all the time. I want to thank Danielle, Chris, and Jonathan for sparking them up in my mind again and for creating lovely spaces for conversations in their afternoon sessions.


Coming soon will be my last entry in this series where I think out loud about the amazing keynote delivered by Tracy Zager (@TracyZager)

TMC16 Reflections, Part One

I’ve been trying to sort out my thoughts from the past week in Minneapolis and I have found that one of the best ways for me to do this is to sit and type them out. I am thinking that I may partition these reflections into three or four parts over the next day or two so that the ideas I am wrestling with will feel more bite-sized to me. Lil’ Dardy just had a terrible dental appt this morning so I am home with her all day. This will give me some writing time as she just naps away her pain and discomfort.


First, I want to concentrate on a small roundtable discussion section that I had proposed. I called it Building our own MTBoS at Home. A little background helps. I work in a small independent, day and boarding, PK – PG, co-ed school. I have five full-time colleagues in my department in our high school. Our other campus is three miles away and that is where my two children attend school. There are few other independent schools in my area and I have not found a way to connect logically with the public schools in my region. When I proposed this session I was hoping to crowd source some wisdom. I LOVe the online community I have tapped into and I suspect that if you are reading this that you do too. I also know that as valuable as you all are as an online resource, it is even better when I can sit down face-to-face to share ideas and energy. That is one of the beauties of the Twittermathcamp (TMC) experience. So, I was hoping to gather some ideas about how to build outreach so that we can find some of the same sustenance that comes from TMC more regularly in our home areas.


One of the GREAT problems posed by attending TMC is that every session slot has multiple promising events occurring. I was happy to have five energetic folks come to my session. I know that Sam Shah (@samjshah) and Tina Cardone (@crstn85) had a session with a  similar theme happening the next day. I look forward to picking their brains to see what came out of their session. A couple of the folks in my room where newbies to the TMC experience and it was great to hear what was on their mind. Our speaker at the Desmos pre-conference challenged us to think of evangelist as part of our job title, so that was on my mind all weekend. As we chatted in my session this idea kept coming up. Glenn Waddell (@gwaddellnvhs) spoke eloquently about his journey building community in Nevada. The phrase that came to my mind listening to him was ‘death by a thousand paper cuts.’ He spoke of sending out emails with links to administrators and other teachers every Monday. Simple, short links with a friendly message along the lines of ‘I saw this in my feed and thought it might be helpful.’ Every Monday – this is the part that really resonated with me. Be persistent, be consistent, be short and to the point. There is a local group that runs a math competition in the spring here – usually during our spring break, unfortunately – and I want to reach out to them. I want to find the email address of math teachers at my local schools. My goal this year is to build a couple of email group with addresses of these folks and reach out and share on a regular basis. Currently, I have been in the habit of emailing (or tweeting) links to colleagues – both those in my building and my online community – whenever I see something interesting. I think that I am going to adopt Glenn’s idea and make it sort of a weekly roundup. Perhaps I will use this space as the forum for my online team to share out ideas I have gathered or developed in addition to sharing out my classroom experiences. The other big idea I took away from Glenn was that he arranged a sort of happy hour meeting with some teachers in his area and, through the help of some grant money was able to provide some appetizers. He said that he also shared out some ideas regarding improving personal efficiency through some nice applications in addition to discussing class ideas. So he summarized by saying that he was able to provide a space that age each teacher three things to takeaway – (1) Some free food; (2) Something to improve their own personal life; and (3) Something to improve their own classroom.


I am pretty confident that I have a model to emulate and I hope to be able to start small with a meeting of local math teachers so that we can start building a support group for each other here in NE PA.


I want to thank all of those who came and I am pretty sure that I got all the names correct. I apologize if I missed someone in my scattered notes or if I got your name wrong. In the room was Kathryn Ramberg (@KathrynRamberg), Chris Robinson (@Isomorphic2CRob), Stephen Weimar (@sweimar), and Mary Langmyer(@mlangmyer)

Please reach out to any of these folks to improve your own community or to continue this conversation of how to enrich our local spaces the way we have enriched the online community that continues to grow. As always, also feel free to poke at me through the twitters where you can find me @mrdardy


A String of Good News

Our school year ends early, we graduate the day before Memorial Day here. So, I have had some time to unwind AND to look ahead to next year. I’ve been thinking about my new Discrete Math text, problem sets for my AP Calculus BC class (thanks to inspiration from Lisa Winer (@lisaqt314)), and my upcoming trip to TMC where I will be hosting a brief session to discuss how to develop communities similar to our MTBoS back at home.

Recently, I received not one, not two, but THREE pieces of good news that has happily distracted me a bit from thinking about the fall.

Last summer I led a session at the Pennsylvania Teachers of Mathematics summer conference. I gave it the dramatic title Escaping the Tyranny of the Textbook and it is essentially my love note to the MTBoS community. The goal of the presentation was to have any participants in the session leave the room feeling empowered to write their own curriculum or to learn better how to crowdsource curriculum that is tailored for their classrooms. I was pretty happy with it but I know it needs to be punched up. What better motivation to improve something than to put yourself in a public position where you need to be up in front of people all over again? So, I sent proposals to two upcoming conferences and I learned in the past few weeks that I was accepted to both of them! I will be presenting at the fall conference of the Pennsylvania Association of Independent Schools in October and I will be presenting at ECET2NJPA in September. I am flattered that my proposal was approved by each of these conferences and I am excited to meet some new folks to expand my circle of colleagues even more.

Our school started a STEM initiative shortly after I arrived here in 2010. The first director of the program has decided to step down in large part due to other responsibilities that she has since taken on. She has put the program on firm footing and when he school announced this opening they committed to having a director and two associate directors. I received the great news last week that I will be one of the associate directors of the program. All of our freshman take a STEM class that was designed by the program director and some of our students. They created some lovely iBooks that are still works in progress and that I feel a kinship to since I created our text for Geometry in a similar fashion. We have been hosting guest speakers, alumni, panels of regional experts to discuss items of interest. It’s an exciting program and I am looking forward to being part of the team for the next year. If any of you have advice regarding possible directions for STEM programming, please share here in the comments or over at twitter where I am found @mrdardy


How to Succeed

Feedback from my students at the end of the year touched, in part, on the idea that many of my students take some time to adjust to my expectations in our course. Years ago, I wrote a document called How to Succeed in Calculus. This was adapted from a document I found online by a teacher I never met named Dave Slomer. I have modified that document for my Geometry class and I want to share my first draft here. I shared it with my Geometry team and we have a nice conversation started about how to introduce and integrate this document. The first reaction from one of my colleagues is that the document might be a tad too long and students might easily put it aside. I agree that it is a bit wordy but I also feel that there is not much that I want to cut out. I would love any constructive feedback either here or through my Twitter account over @mrdardy

Here is my first draft –

How to succeed in Geometry
Over the years, I have found that the best indicator of a student’s success is whether they keep up with their assignments. Students who keep up will likely do well – students who don’t likely won’t. We will be together for a good amount of time this year and we will routinely refer back to ideas and skills that we have discussed together. If you do not keep up with your assignments then it will become increasingly difficult for you to master new skills.

You understand the material best when you can do the problems – and get them right – BY YOURSELF. There is absolutely nothing wrong with asking questions or seeking help from me, from other teachers, or from your fellow students. Everyone will need help sooner or later in this course. However, you must have the integrity to realize that the goal of the assignment is NOT just to get the assigned problems done. When we write our problem sets we are aiming to make sure that there is sufficient practice for all of our students. However, there will be times when you will need more practice than this, and you must have the courage and integrity to realize it. When you ask for extra practice, we can provide you with assignments that will help you to master new skills.

If you take your homework problem sets seriously, if you spend time thinking and working through the problems we present to you, you will feel more prepared for tests and quizzes than if you do not. Hard work spent on daily practice pays off on test days. Athletes who take practice seriously are better prepared for game days. Musicians and actors who take rehearsals seriously are better prepared for performances. Students who take daily practice seriously are better prepared for assessments. We know this to be true.

Your problem sets have narrow spaces available. Do not try to squeeze all of your work in these spaces. It is unlikely that you will be able to read your own work when you look back at your work and it is very unlikely that I’ll be able to clearly see your work and understand your reasoning. Do your work on notebook or blank paper and give yourself space to draw and to think.

If you hit a “dead end” and want to start over, cross out the work you don’t want with a big “X” – do NOT erase it. It might turn out later to be correct. Also, if you come to me for help, the first thing that I will say is “Let me see what you have done so far.” If you tell me that you erased it, it will be much harder for me to help you. Erasing can be a big time-waster on tests (where time is very valuable).

This is important in every class, but in this class the text serves as a valuable supplement to what happens in class. Often your homework will be to read the book in addition to any of the problem sets that we have written. Read the book carefully with a pencil and paper nearby. Pay particular attention to the illustrations and examples. Study the examples carefully. All of you have access to a PDF of the text and some of you will also have opted to have a physical copy of the text as well. Use your physical copy, if you have one, for margin notes. Use your PDF regularly to follow hyperlinks to explanations and activities that have been built in to your text. These are valuable resources and we expect that you will attend to them when you are asked to read.

It is vitally important that we can communicate in the language of mathematics. As you read or participate in class, pay particular attention to the meaning of each new term and symbol. This is a course that is heavy on vocabulary, you need to spend time and energy on this aspect of your study of Geometry.

Luckily for you, tests are cumulative, and we will review in class; therefore review is somewhat automatic. Don’t hesitate to go back to review or seek help on algebra skills or on earlier ideas from this course that you may not have mastered as well as you wanted to.

Good notes are essential for success in any technical field. They are essential for review – not only for tests, but also for the problems you will work that evening. It is far too tempting to sit and listen and watch during class. You may feel comfortable at times following our conversations this way. However, when you sit down at night to do your homework, you will be without a valuable resource and you may not remember well what the conversation was hours ago when we were together in class. Every study of learning that has ever been done suggests that the act of writing something down helps in strengthening our memory. It is my expectation that each of you will come prepared each day to take notes on our class conversations.
You need to use the time at the beginning of class to get ready for geometry. Get out your books, assignments, notebooks, pencils, etc. I will usually have a question on the board or the TV monitor when you arrive in class. Get to work on that and get your mind in its math mode. Socializing may be more pleasant than math, but the goal is to make math more pleasant, and socializing often gets in the way. At the end of the discussion period, begin (or continue) the current assignment right away – what better time to get help if you get stuck? We only spend valuable class time on important topics, so take good notes constantly during class.

Your success depends on your ability to recall (or find, relearn, and then remember) concepts and techniques that were introduced earlier. If your notes and assignments are scattered about, folded inside the covers of your book, papering the bottom of your locker or the floor of your bedroom, you’re sunk.

There are many students, and just one teacher, and time is too valuable for you to just wait – stuck in neutral – for help. Look in your text and your notes for sample problems that might shed some light on your difficulty. Learn tenacity – don’t just “fold” at the first sign of difficulty. Is there another way to approach the problem? You can do it.

Everyone, no matter how smart or proficient in math, will get stuck sometime this year. Perhaps there is a new concept or technique that just won’t fit into place in your brain. Tenacity and self-sufficiency are great attributes, but sometimes there is going to be a quiz on this stuff tomorrow. Sometimes there just isn’t time to be tenacious. Attend conference bells, ask questions in class, just be sure to get the help you need to succeed.

If you have a worry, complaint, suggestion, or concern of any kind let me know. I can’t fix it if I don’t know about it. Remember that just because a problem – or a solution – seems obvious to you, it may not be obvious to everyone. Speak up.


There are some things I do in class that you may find unorthodox. If we understand each other early in the year, we’ll avoid a lot of stress later in the year. There are mathematical facts that I expect you to know and I will remind you that you should know them. There are times when you will ask a question and I may reply with a question. Or, I may redirect the question to someone else in class. This is not done to avoid answering a question, it is done to encourage a thoughtful discussion and to help you to develop important problem solving skills. I believe strongly that we understand ideas more deeply if we can explain our own thoughts to others. For this reason, we sit in groups facing each other, rather than having everyone face me or face the board. I expect that you will explain ideas to each other and that you will ask each other questions. Questions in this class will ALWAYS be answered; you may just have to be patient before the answer arrives.

A quote by Galileo Galilei

“Philosophy [nature] is written in that great book which ever is before our eyes — I mean the universe — but we cannot understand it if we do not first learn the language and grasp the symbols in which it is written. The book is written in mathematical language, and the symbols are triangles, circles and other geometrical figures, without whose help it is impossible to comprehend a single word of it; without which one wanders in vain through a dark labyrinth.”


Thinking Out Loud

Super brief post here – class starts in 15 minutes. One of my Geometry colleagues asked me about a HW question I had written. I asked the students to find two cylinders that were not congruent but that had the same surface area AND the same volume. I thought it was a pretty interesting question, but I realized I did not have a coherent strategy for discussing it other than playing with numbers. I threw the question out to Twitter and engaged in a terrific conversation with Matt Enslow (@CmonMattTHINK), John Stevens (@Jstevens009), Dave Radcliffe (@daveinstpaul), and David Wees (@davidwees) Some good math was tossed around, but what really has my brain bubbling is an exchange with David Wees. He said he thought it was a great question but he would not have used it as a homework question. When I asked him why he said something that reminded me of a conversation with a former colleague. My former colleague once said that he sees a difference between exercises and problems and that he liked to keep problems for times together with the students where they could work together. I find that I feel (hope) that meaningful conversations can happen in class more readily about a problem like this one if the students have had time to think about it first. However, his words carry some weight with me as do David’s. I feel as if there is some conclusion I want to reach, but I also suspect that there is no right answer to this. I would love to hear some opinions about this in the comments or through Twitter where you find me at @mrdardy



A Geometry Explanation Idea

Today will likely be a two post day after too long of a layoff from this space. It’s funny, I know that this writing relaxes me and lets my brain breathe in important ways. However, I am too prone to let busy-ness in my life prevent me from taking advantage of that.

In Geometry we are examining relationships between angles and arcs. You know the drill, right? Central angles = intercepted arc measure. Inscribed angles are equal to half of the measure of their intercepted arc. Interior angles (other than those at the center) are equal to half of the sum of their intercepted arcs. Exterior angles equal half of the difference of their intercepted arcs. As I am explaining this yesterday in class I am emphasizing this half relationship over and over but I just kind of gloss over the fact that the central angle does not fit this pattern. I have gone through this explanation in the past but I do not think I was as explicit about the developing pattern with the one half scale factor in the past. So this morning I was thinking about how I can best help my students focus on this detail. I was motivated, in part, by a lovely blog post by Michael Pershan (@mpershan) which, in part, is about managing the processing load of our students. I was struck when reading by the fact that I was asking my students to juggle seemingly different rules yesterday. So I had this idea and it probably is not revolutionary in any way. But I think I want to simply say that central angles are interior angles. They happen to be interior angles that form two congruent arcs. This way I can ask my students to think about the one half scale factor for every angle/arc question that they think about.

Does anyone else out there do this? Do you agree with this idea? Do you think that there is a downside here that I am not seeing yet? I’d love to hear some thoughts in the comments or you can find me over on twitter @mrdardy


Thinking out Loud…

A super brief post here – hoping to find some great advice from the world outside.

Two years ago our school launched a Discrete Math course. We realized that we had a number of students who were not being served well by our curriculum – a relatively standard one, really – that served to deliver most of our students to the doorstep of Calculus. I loved Calculus as a student and I have been happy to teach some form of it for most of my teaching career. However, we realize as a department that not all of our students need to see Calculus as the pinnacle of their high school math career. We also offer AP Statistics but we still saw a groups of students who were not being served properly. We have a vision of this Discrete Math elective being a lively, provocative course that exposes these students to more (and different) mathematical ways of thinking. We adopted the text For All Practical Purposes (9th Ed) and in the first year we had the course, the publisher released a new edition. I am teaching the course this year and I really like the students in the course and I feel that we are making some real progress in showing a different side of mathematical thinking, something other than algebraic reasoning and equation-based mathematics. However, I am not thrilled with the text. I am not sure that the level of the writing is suited well to my kiddos and I spent most of the fall term writing my own problem sets. Since the text is not available anymore I am faced with a choice of moving on the the 10th edition, finding a new text to serve as the center of the course, or going text-free and writing/borrowing unit notes and problem sets to support the students.

I know that there are people who visit my space here who have experience with math electives outside of the algebra to Calculus stream. I would love to hear some advice from them either in the comments here or through my twitter feed (I am @mrdardy over in the twitterverse) The ability / interest level of the students varies in this group. Some are taking the math course out of good conscience/concern about the college process. They know it is a ‘good idea’ to have a fourth math course. Some are taking it to fill out their schedule. Some end up in it after dropping back a bit from another math course that was more of a challenge than we/they expected it to be. This year we spend some time on elementary statistics/probability already. We spend a little time in the fall getting ready for a last swing at standardized tests. We are currently immersed in a unit on elections and voting strategies. We will visit some finance ideas and we will dip our toes into graph theory / network theory ideas. I am not married to any of these particular ideas, but many of them pop up in most discrete math text options out there. I kind of love Jacobs’ text Mathematics: A Human Endeavor but it seems not to be currently in print and I do not want to go down the path of a text I cannot reliably get my hands on.

So, dear readers, I would appreciate any wisdom you can share from experiences at your schools.

Why Do We Teach our Students (_________________)?

A quick post here as I get ready for our first full day of staff meetings. Yesterday, at a lunch with department chairs for our lower school and our upper school, one of my colleagues raised a nice question. We were discussing our goals for this afternoon’s joint department meetings and we were bouncing around some topics related to summer reading, content alignment, etc. We are a PK – 12 school but we are on two campuses separated by three miles so we do not see each other as often as we would like. Meetings like the one we will have this afternoon are few and far between. So, the question raised by one of the chairs was this – ‘Why do we teach, fill in the blank?’ In other words, can our English teachers say something similar to each other about why we teach English? Can my math team say something coherent and cohesive about why we teach math? I titled this blog post the way I did in honor of Glenn Waddell (@gwaddellnvhs) who reminded us this summer at TMC15 that it is important to remember that math is the subject we teach (at least all of us there!) but we teach people.

So, what would you say in response to the question ‘Why do you teach math to young people?’ Why do you teach chemistry to young people?’

I think I have an elevator speech in mind but I realize, when pressed, that it is not as succinct as I would like it to be and I am not convinced that there is enough overlap between my reason and those of my departmental colleagues. I think that, for the benefit of our students and for coherence in our program, that we should probably share this question with each other. I would love to hear in the comments or over at twitter (I am found there @mrdardy) what you think of this question and what your answer is.

Off to full faculty meeting starting in 33 minutes!