A couple months ago, my colleague Jeff Rushall and I co-applied for a Center for Undergraduate Research in Mathematics (CURM) mini-grant to fund a group of undergraduate students to work on an academic-year research project. Jeff and I had both individually applied in the past, but neither of us were successful in our proposals. If you are interested, you can take a look at my previous proposal by going here. Jeff and I are both passionate about undergraduate research and work well together. We decided that a joint application would likely be stronger than two individual proposals. I’m happy to report that we recently found out that our proposal was funded. We’re thrilled!

Here are a few more details. For the upcoming project, we have recruited a diverse group of 7 talented undergraduates for this project: Michael Hastings (one of my current research students), Emily White, Hanna Prawzinsky, Alyssa Whittemore, Levi Heath, Brianha Preston, and Nathan Diefenderfer. Students are expected to spend ten hours per week during the academic year working on the research project. In return, each student will earn a $\$3000$ stipend. Money from the grant will also be used to buyout a single course for both me and Jeff. In addition, Jeff and I will team-teach a topics course each semester that will include our research students but will also be open to other interested students. CURM will cover most of the travel expenses for Jeff and I to attend the Faculty Summer Workshop at Brigham Young University (BYU). CURM will also cover most of the travel expenses for the nine of us to attend the Student Research Conference at BYU.

A collaborative research program has many advantages over operating several disconnected projects, as Jeff and I have done in the past. One of our goals is to build a self-sustaining research group. Ideally, this group will consist of students at different stages of their education, each participating for multiple years. The opportunities afforded by a CURM mini-grant will provide a catalyst for our endeavor in several ways. First, the visibility of a student research group with a CURM mini-grant will help our department recruit mathematically inclined students. NAU has many such students, but some are enticed by existing research groups and grants in our science programs. Second, we would like to take advantage of the mentoring and training the CURM program provides for faculty. One weakness in my past projects is getting students to finish writing up their results for publication. I am hopeful that my involvement in CURM will help remedy this. Third, we believe that the stipend money will enable our students to forgo some of their part-time work and instead devote their time to mathematics. Lastly, we want to use the experience as a stepping stone towards obtaining an externally funded REU program.

Next year’s research project involves “prime labelings of graphs,” which is outside my typical research interests. Jeff and I believe that we have found a project that is accessible to undergraduates yet rich enough that we won’t even come close to running out of stuff to do. I’m really looking forward to branching out and exploring something new.

If you are interested, here is the project description that we submitted.

Project Description

This research project is motivated by a conjecture in graph theory, first stated in a 1999 paper by Seoud and Youssef [1], namely:

All unicyclic graphs have prime labelings.

This is a viable choice as a research problem for undergraduates because it is interesting yet accessible, in large part due to the minimal amount of background information required. To wit, a unicyclic graph is a simple graph containing exactly one cycle. An $n$-vertex simple graph $G$ with vertex set $V(G)$ is said to have a prime labeling if there exists a bijection $f: V(G) \to \{1, 2, 3, \ldots, n\}$ such that the labels assigned
to adjacent vertices of $G$ are relatively prime.

As discussed in Gallian’s “A Dynamic Survey of Graph Labeling” [2], many families of graphs have prime labelings; the “simpler” types of unicyclic graphs that are known to have prime labelings include cycles, helms, crowns, and tadpoles. The goal of our project will be to discover additional classes of unicyclic graphs with prime labelings, in hopes of bringing the aforementioned conjecture on all unicyclic graphs within reach. The families of graphs we will investigate include, but are not limited to:

  1. double-tailed tadpoles, triple-tailed tadpoles, etc.;
  2. irregular crowns (crowns with paths of different lengths attached to each cycle vertex);
  3. unicyclic graphs with one or more trivalent trees attached to cycle vertices;
  4. unicyclic graphs with one or more complete ternary trees attached to cycle vertices; and
  5. unicyclic graphs with a specified number of non-cycle cubic vertices.

Seoud and Youssef have established necessary and sufficient conditions for some graphs to have prime labelings, but they are somewhat limited in scope. Seoud has also published an upper bound on the chromatic numbers of prime graphs. These and other results may be beneficial to our students as their research project progresses.

Ernst and Rushall have already made some progress on these specific cases. We will use these initial results as a starting point with our team of students. More precisely, the 7 students involved in this project will attend a 3-credit research seminar during both semesters of the 2014-2015 academic year. Ernst and Rushall will team-teach the seminar, but eventually the students will play an equal role in leading discussions, presenting research results, etc.

Our recent experience with Seoud’s Conjecture has indicated that this problem is ripe with potential and highly appropriate as an undergraduate research project. The students can begin productive work in a single afternoon, and yet we anticipate the students producing original results worthy of publication in refereed journals by the end of the academic year. Moreover, there appear to be a virtually unlimited number of families of graphs to investigate, which will hopefully lead to a sustainable research program for undergraduates in future years.

The 7 students we have recruited to work on this research project are mathematics majors in our department. In addition, they all have very good academic records, and have proven themselves to be hard-working, reliable and creative students in previous courses that we have taught, including vector calculus, linear algebra, abstract algebra, foundations, discrete mathematics and number theory. These students regularly attend our weekly departmental undergraduate seminar, so they are familiar with the rigors associated with research and are motivated to investigate deeper problems in mathematics.

It should be noted that several presentation venues (departmental, university-wide, as well as regional conferences) will be exploited to allow our students an opportunity to showcase their efforts during the 2014-2015 academic year.

References

[1] M. A. Seoud and M. Z. Youssef, “On Prime Labeling of Graphs,” Congressus Numerantium, Vol. 141, 1999, pp. 203-215.

[2] J. A. Gallian, “A Dynamic Survey of Graph Labeling,” The Electronic Journal of Combinatorics, Vol. 18, 2011. http://www.combinatorics.org/Surveys/ds6.pdf

Undergraduate Student Poster Session

The Joint Mathematics Meetings took place last week in Baltimore, MD. The JMM is a joint venture between the American Mathematical Society and the Mathematical Association of America. Held each January, the JMM is the largest annual mathematics meeting in the world. Attendance in 2013 was an incredible 6600. I don’t know what the numbers were this year, but my impression was that attendance was down from last year.

As usual, the JMM was a whirlwind of talks, meetings, and socializing with my math family. My original plan was to keep my commitments to a minimum as I’ve been feeling stretched a bit thin lately. After turning down a few invitations to give talks, I agreed to speak as part of panel during a Project NExT session. The title of the panel was “Tried & True Practices for IBL & Active Learning”. Here, IBL is referring to inquiry-based learning. Last year I gave several talks and co-organized workshops about IBL, so I knew preparing for the panel wouldn’t be a huge burden.

The other speakers on the panel were Angie Hodge (University of Nebraska, Omaha) and Anna Davis (Ohio Dominican University). Each of us were given 15 minutes to discuss our approach to IBL and active learning and then we had about 20 minutes for questions. For my portion, I summarized my implementation of IBL in my proof-based courses followed by an overview of my IBL-lite version of calculus. Angie discussed in detail the way in which UNO is successfully adopting IBL in some of their calculus sections. Anna spent some time telling us about an exciting project called the One-Room Schoolhouse, which attempts to solve the following problem: Small colleges and universities often struggle to offer a variety of upper-level courses due to low enrollment. According to the ORS webpage, the ORS setting allows schools to offer low-enrollment courses every semester at no additional cost to the institution. ORS is made possible by flipping the classroom.

If you are interested in my slides, you can find them below.

I’m really glad that I took the time to speak on the panel. The audience asked some great questions and I had several fantastic follow-up conversations with people the rest of the week.

As a side note, one thing I was reminded of is that speaking early during the conference (which is when the panel occurred) is much better than speaking later. The past couple JMMs, I spoke on the last day or two, and in this case, my talk is always taking up bandwidth in the days leading up to it. It’s nice to just get it out of the way and then be able to concentrate on enjoying the conference.

One highlight of the conference was having a pair of my current undergraduate research students (Michael Hastings and Sarah Salmon) present a poster during the Undergraduate Student Poster Session. Michael and Sarah have been working on an original research project involving diagrammatic representations of Temperley-Lieb algebras. I’ve been extremely impressed with the progress that they have made and it was nice to be able to see them show off their current results. The title of their poster was “A factorization of Temperley–Lieb diagrams” (although this was printed incorrectly in the program). Here is their abstract:

The Temperley-Lieb Algebra, invented by Temperley and Lieb in 1971, is a finite dimensional associative algebra that arose in the context of statistical mechanics. Later in 1971, R. Penrose showed that this algebra can be realized in terms of certain diagrams. Then in 1987, V. Jones showed that the Temperley–Lieb Algebra occurs naturally as a quotient of the Hecke algebra arising from a Coxeter group of type $A$ (whose underlying group is the symmetric group). This realization of the Temperley-Lieb Algebra as a Hecke algebra quotient was generalized to the case of an arbitrary Coxeter group. In the cases when diagrammatic representations are known to exist, it turns out that every diagram can be written as a product of “simple diagrams.” These factorizations correspond precisely to factorizations in the underlying group. Given a diagrammatic representation and a reduced factorization of a group element, it is easy to construct the corresponding diagram. However, given a diagram, it is generally difficult to reconstruct the factorization of the corresponding group element. In cases that include Temperley–Lieb algebras of types $A$ and $B$, we have devised an efficient algorithm for obtaining a reduced factorization for a given diagram.

Perhaps I’m biased, but I think their poster looks pretty darn good, too.

All in all, I would say that I had a successful JMM. I had a lot more meetings than I’ve had in the past, so I missed out on several talks I really would have liked to attend. There’s always next year.

A summary of 2013

January 4, 2014 — Leave a comment

DanaHere’s a quick run down on the annual stats for my blog according to Jetpack. For the complete report, go here.

This blog was viewed about 16,000 times in 2013. My teaching page is a subdomain of my main site, so I’m guessing that a good chunk of that 16,000 is a result of my students clicking around (but I’m not sure about that). In 2013, there were 29 new posts, growing the total archive of this blog to 63 posts.

The busiest day of the year was September 18th with 340 views. The most popular post that day was Free and Open-Source Textbooks.

The top five most viewed posts in 2013 were:

  1. LaTeX Homework Template, Aug 2012
  2. Mathematics Education on the arXiv?, Jul 2013
  3. Montessori Observations, Apr 2013
  4. An infinite non-cyclic group whose proper subgroups are cyclic, Dec 2013
  5. Euler’s Research Rules, Oct 2013

The top referring sites in 2013 were:

  1. Twitter
  2. Google+
  3. Facebook
  4. My Teaching Page
  5. Booles’ Rings

I would have expected Google+ to be the top referrer and I’m a bit surprised that Facebook made the list at all. I’m happy to see that being a part of Booles’ Rings (a network of academic home pages/blogs) is bringing some traffic this way and I hope that I’m reciprocating at least a little.

Visitors came from 114 different countries! Most visitors came from the United States, but Canada and the United Kingdom were not far behind.

The most commented on post in 2013 was Mathematics Education on the arXiv? with 26 comments. These were the 5 most active commenters on this blog:

  1. Dana Ernst, 26 Comments
  2. François G. Dorais, 7 Comments
  3. Bret Benesh, 4 Comments
  4. Simon H., 3 Comments
  5. Peter Krautzberger, 2 Comments

I guess it’s no surprise that I was the top commenter. It is worth pointing out that François and Peter are also members of Booles’ Rings.

Thanks for a fun year!

Nice socks!

December 28, 2013 — 1 Comment

socks On page 36 of the December 2013/January 2014 issue of the MAA FOCUS there is a short article about Math Ed Matters, which is a monthly blog/column sponsored by the Mathematical Association of America and coauthored by Angie Hodge and myself. The article, written by Katharine Merow, highlights a few of our recent posts and describes some potential future posts (I should write these down, so we remember to write the advertised posts!). Katharine wanted to include a picture of Angie and me for the article, and as you can see in the picture to the left, she chose one of us that was taken after we had finished a trail run. I’m also wearing some ridiculous looking socks! The socks are actually compression socks designed for running, but they look silly nonetheless. I’ve been getting some flak for wearing such tall socks, but I think it’s funny.

I knew this article was going to appear, but I wasn’t sure when. It was brought to my attention by Robert Jacobson via one of his Google+ posts. Robert is responsible for the photo.

Q8The Fall semester of 2013 just ended and one of the classes I taught was abstract algebra. The course is intended to be an introduction to groups and rings, although, I spent a lot more time discussing group theory than the latter. A few weeks into the semester, the students were asked to prove the following theorem.

Theorem. If $G$ is a cyclic group, then all the subgroups of $G$ are cyclic.

As with all conditional theorems, I also encouraged my students to think about whether the converse of this theorem is true. That is, if all the subgroups of a group $G$ are cyclic, does this imply that $G$ is cyclic? Well, since $G$ is always a subgroup of itself, the answer is clearly yes. But this isn’t the interesting question to ask. Instead, we should ask:

If $G$ is a group such that all proper subgroups are cyclic, does this imply that $G$ is cyclic?

The answer is “no” and my students were able to quickly come up with a few counterexamples. In particular, they mentioned the dihedral group $D_3$ (symmetry group for an equilateral triangle), the Klein four-group $V_4$, and the Quarternion group $Q_8$. The groups $D_3$ and $Q_8$ are both non-abelian and hence non-cyclic, but each have 5 subgroups, all of which are cyclic. The group $V_4$ happens to be abelian, but is non-cyclic. Yet it has 4 subgroups, all of which are cyclic.

Following the discussion of these three examples, one of my students asked whether the question above is true for infinite groups. I responded with something like, “Uh…well…no, I don’t think so. Hmmm, let me think about it.” So, I thought about it off and on for a couple hours, but didn’t make much headway. I decided to roam the hallways and recruit some help. I ended up chatting with my colleagues Mike Falk, Jim Swift, and Jeff Rushall. Collectively, we all thought about it a little bit here and a little bit there. I was fairly confident that an internet search would provide some insight, but I was intentionally putting that off in the hopes that I could come up with an example.

A couple days later, I was meeting with one of my undergraduate research students and we chatted briefly about the problem. A few hours after we met, he sent me a link to a discussion on Math Stack Exchange, which contains a response that is precisely about the question above.

Without further ado, here’s an example that confirms that the answer to the question above is “no” even if the group is infinite.

Theorem. The group $G=\{a/2^k\mid a\in\mathbb{Z}, k\in\mathbb{N}\}$ is an infinite non-cyclic group whose proper subgroups are cyclic.

Note that any fixed prime will do for the denominator. Let’s sketch a proof.

First, it is clear that $G$ is an infinite subgroup of $\mathbb{Q}$ since the sum of any two elements from $G$ will be contained in $G$ and the additive inverse of any element from $G$ is also in $G$. To see that $G$ is not cyclic, let $a/2^k\in G$ such that $a$ is odd and consider $\langle a/2^k\rangle$. It’s quickly seen that $\langle a/2^k\rangle$ does not contain any rational numbers having denominators equal to $2^{n}$ for $n>k$, and hence $G$ is not cyclic. Now, suppose that $H$ is a proper subgroup of $G$. If $a/2^k\in H$, then $a/2^{k-1}=a/2^k+a/2^k\in H$, as well. It follows that if there is an element in $H$ with denominator equal $2^k$ (in reduced form), then $H$ also contains elements with denominators equal to $2^n$ (in reduced form) for all $n\leq k$. Since $H$ is a proper subgroup, there exists a smallest $m\in \mathbb{N}$ such that no element of $H$ has a denominator equal to $2^m$. Then it must be the case that $H$ is contained in $\langle 1/2^{m-1}\rangle$, and so $H$ is cyclic (since subgroups of cyclic groups are cyclic).

Cool.

Do hard things

December 3, 2013 — Leave a comment

Zach GoldenbergRecently one of my former students at Plymouth State University, Zach Goldenberg, was awarded the 2013 Graduating Senior Award of Excellence. Zach is an amazing person and the award is well-deserved. I was fortunate to have Zach as a student in several of my classes, including Calculus I, Calculus II, Intro to Proof, Number Theory, and Abstract Algebra. As a freshman, he was the top student in both calculus courses. In the other courses, he consistently stood out as one of the top students. In addition, Zach was one of four undergraduate research students that worked on an original research project with me during the 2010–2011 academic year. Along with his fellow researchers, Zach presented the findings of their research at two regional conferences and presented a poster at the Joint Mathematics Meetings. Zach was instrumental in the success of this research group. Zach graduated summa cum laude with a double major in mathematics and political science. He was heavily involved with service opportunities, giving back in the local community at the Pemi Youth Center and internationally through his work with PSU’s Nicaragua Club and as an intern with Compas de Nicaragua, a non-profit organization dedicated to improving lives in urban and rural Nicaragua.

One of the things that I like best about Zach is his enthusiasm for life. His positive attitude is contagious and makes him an absolute pleasure to be around. He is constantly smiling and providing words of encouragement to those around him. Zach has been an exceptional role model for others by demonstrating that hard work pays off, and that the right attitude can make the difficulties and challenges enjoyable.

Below is a short video in which Zach was able to provide us with some words of wisdom.

When asked whether he had any advice for future students/graduates, Zach responded with:

Do hard things. It’s not that I want people to try and fail at things, but even if they do try and fail, that sometimes is the best experience that you can have. Try to do impossible things; you’d be amazed at how much you grow in just trying to do that. Try to do something bigger than yourself.

This dude is going to help change the world for the better. Well done Zach!

Zach’s perspective resonates with the reasons that I choose to teach via inquiry-based learning (IBL). Of course, I want my students to learn mathematics in my classes, but what I really want is to provide them with an opportunity to have a transformative experience. I want my students to yearn for challenges and to learn to turn their stumbling blocks into stepping stones.

On Thursday, October 17, I gave an hour long talk in our department seminar titled “An Iterated Prisoner’s Dilemma.” There were about 35 people in attendance, including undergraduates (mostly my calculus students), graduate students, and faculty from the Mathematics & Statistics Department at Northern Arizona University. I was pleased with the turnout since our seminars are usually on Tuesdays and I wasn’t sure how many people would come on a non-standard day. Here is the abstract for the talk:

The Prisoner’s Dilemma goes something like this. Two members of a criminal gang are arrested and imprisoned. Each prisoner is in solitary confinement with no means of speaking to or exchanging messages with the other. The police admit they don’t have enough evidence to convict the pair on the principal charge. They plan to sentence both to a year in prison on a lesser charge. Simultaneously, the police offer each prisoner a bargain. If A and B both confess the crime, each of them serves 2 years in prison. If A confesses but B denies the crime, A will be set free whereas B will serve 3 years in prison (and vice versa). If A and B both deny the crime, both of them will only serve 1 year in prison. In this talk, we will first discuss this classic game theoretic problem and then introduce an iterative version that consists of a round robin tournament of teams, where the winner is the team that spends the least amount of time in prison.

I pretty much lifted this straight from the the Wikipedia page on the Prisoner’s Dilemma. So, thanks to the author(s) of that page!

There were several motivating factors in choosing this topic. First, every once in a while, I like to give a talk about something that I don’t know much about. Doing this forces me to learn something new. Also, I’ve found that some of my best talks are on things that I am not an expert on. Certainly, one of the reasons why this is true is that I’m likely to pitch a talk at a lower level if I’m talking about something unfamiliar. I don’t know about you, but I much prefer sitting through a talk when I understand most of what’s going on. Culturally, it seems acceptable to give talks where most of the audience doesn’t understand most of the talk. I’m trying to give talks where this doesn’t happen.

It’s expected that our graduate students (we have a masters program at NAU) attend our weekly seminars, but lately their attendance has been poor. I wanted to pick a topic that might entice them to start coming.

I ended up choosing the Prisoner’s Dilemma as a topic because I wanted to learn more about game theory and I figured the topic would be accessible. Moreover, I was inspired by Google+ and blog posts by Vincent Knight and Paul Harper (both from Cardiff University). There was also an excellent Radiolab episode about the Prisoner’s Dilemma back in 2010 that planted a seed for me. I’d like to thank Vince and Paul for helping out while I was preparing my talk. In particular, my slides are a modification of Vince’s slides, which he discusses here.

Without further ado, here are the slides for my talk.

As you can see, the talk began with an activity involving the Two Thirds of Average Game. During the activity, the audience made two different guesses. While I was giving the rest of the talk, I had a volunteer enter all the guesses into a csv file on the Sagemath Cloud. At the end of the talk, I ran Vince’s python script on the csv file in the Sagemath cloud. The output told me who the winners were for both rounds of guessing and provided a dandy looking graph, seen below.

Results for 2/3 of Average

I provided the winners with some chocolate.

Around slide 18, the plan was to conduct an Iterated Prisoner’s Dilemma tournament involving 4 teams, but I was a little worried about running out of time. So, I decided to wait until the end of the talk and do it if I had time. I ended up squeezing in a 3-team tournament that we probably flew through too quickly to get much out of, but it was fun nonetheless. The three team names were the United States, North Korea, and Russia. North Korea ended up winning, but only by a small margin.

Several weeks ago, links to a survey article by Jeffrey Lagarias about Euler’s work and its modern developments and a blog post by Richard J. Lipton that discusses Lagarias’ paper were circulated on Google+. I’d like to thank Luiz Guzman and Joerg Fliege for first bringing these items to my attention.

Lagarias’ paper is full of lots of yummy goodies, but my favorite part is his summary of Euler’s approach to research (see Section 2.6 of the paper or the end of Lipton’s post).

Euler’s Research Rules

Taken directly from the paper, here is Lagarias’ summary of Euler’s research rules.

  1. Always attack a special problem. If possible solve the special problem in a way that leads to a general method.
  2. Read and digest every earlier attempts at a theory of the phenomenon in question.
  3. Let a key problem solved be a father to a key problem posed. The new problem finds its place on the structure provided by the solution of the old; its solution in turn will provide further structure.
  4. If two special problems solved seem cognate to each other, try to unite them in a general scheme. To do so, set aside the differences, and try to build a structure on the common features.
  5. Never rest content with an imperfect or incomplete argument. If you cannot complete and perfect it yourself, lay bare its flaws for others to see.
  6. Never abandon a problem you have solved. There are always better ways. Keep searching for them, for they lead to a fuller understanding. While broadening, deepen and simplify.

Lipton’s blog post also lists “Euler’s Research Rules.” My main motivation for reposting them here is to remind myself to follow them!

Talk: Proofs without Words

September 30, 2013 — 2 Comments

On Friday, September 20, I gave a 30-minute talk titled “Proofs without Words” during NAU’s Friday Afternoon Undergraduate Mathematics Seminar (FAMUS). As the name of the seminar suggests, the target audience for FAMUS is undergraduates. I usually give a couple talks at FAMUS each semester and this was my first of the semester. Here is the abstract with words for my talk.

In this FAMUS talk, we’ll explore several cool mathematical theorems from a visual perspective.

The talk basically went like this. I displayed a figure or drawing and then the goal was for the audience to come up with the corresponding theorem. I had a ton of fun and the audience seemed to enjoy it. The initial idea for the talk came from the book Charming Proofs: A Journey into Elegant Mathematics by Claudi Alsina and Roger B. Nelsen. This is a wonderful book that incorporates lots of visual proofs. If you don’t have a copy, I highly recommend it. I borrowed lots of ideas from it when I taught a class titled “Introduction to Formal Mathematics” while I was at Plymouth State University.

My original plan was to recreate a lot of the figures I had in mind using TikZ, but I should have known that I wouldn’t have time for that. When I was brainstorming the talk a couple days before, I decided to do a Google search in the hope that I could find some figures to borrow that others had already made. In my search, I stumbled on several references to “proof without words”, which is what I ultimately named my talk. In fact, there is a Wikipedia entry and Roger B. Nelsen also wrote a book called Proofs without Words: Exercises in Visual Thinking. Moreover, I was thrilled to find lots of cool figures on the Internet. For my talk, I borrowed images and content from the following sources:

In the end, my slides ended up being a sample each of these three sources. If you are ready to see some cool figures, check out the slides below. I’ve left the pauses in so that you can ponder the theorem before you see it.

As anticipated, I had more figures than I had time to discuss, but we did get through most of them.

The custom at FAMUS is to interview a faculty member after the 30 minute talk. The usual FAMUS host, Jeff Rushall, was out of town, so I was filling in for him. I had the honor of interviewing Michael Falk. This was fun for me because Mike was my masters thesis advisor.

This past Thursday was the first day of student presentations in my calculus class. It went awesome! The plan is to spend one whole class period each week having students present and discuss problems. The remaining three classes each week will be predominately spent on direct instruction and some small group work. I was emotionally prepared for a crash and burn session as it is often the case that the first day of student presentations in my calculus classes can be a bit rough. I’m totally okay with this as it always improves. But Thursday didn’t leave much room for improvement.

Class started by me asking for volunteers to present their proposed solutions to the problems from their Weekly Homework assignments. I anticipated being met with silence while students stared at their desks. The plan was to then gently nudge people to present. Instead, I had more people volunteer than we had problems. That wasn’t a problem I was expecting. I think I have a good group of students, so I maybe I had nothing to do with this. However, I am suspicious that the heavy marketing that I did helped a lot. Also, I’m curious how much my Achievement Points experiment played into the number of volunteers. Whatever the case, the students were ready to rumble.

In case you are interested, here is the general format for student presentation days, which will typically occur on Thursdays. A few days before the students are to present, I assign a Weekly Homework assignment. You can find the first one that the students did by going here (it’s not terribly exciting). For the most part, the problems on the Weekly Homework assignments are a subset of the material covered the previous week. I’m a big fan of having the students circle back on concepts as much as possible. The students also have Daily Homework assignments that consist almost entirely of problems from WeBWorK.

When the students arrive to class on presentation days, they are supposed to have completed or done their best to complete all of the problems from the Weekly Homework. Upon entering the room, students should grab a colored felt tip pen. I have a box of pens in a variety of colors. The students love the sky blue and purple ones and hardly anyone ever chooses the red ones. During class students can annotate their work only with their felt tip pen. My approach to this is nearly identical to what is described in my Math Ed Matters post located here. The big picture is that I want students to be able to process what they have on their paper as other students are presenting. However, I also want to make sure that I know what work students had done before they entered the room.

One difference between what I describe in the Math Ed Matters post is how I grade the homework that students are presenting problems from. In my other classes where presentations play a more prominent role, the students are presenting problems from their Daily Homework and it is these problems that they annotate with the felt tip pens. In this case, I grade the Daily Homework with a $\checkmark-$, $\checkmark$, $\checkmark+$ system. But in my calculus class, since the students are presenting problems from their Weekly Homework, the students are annotating these problems. Moreover, since students are revisiting topics from the previous week, I feel comfortable weighting the Weekly Homework in calculus more and grading it harshly.

There is no penalty for students using the felt tip pen and I encourage them to annotate to their heart’s content. However, when grading the assignment, the annotations are more or less ignored. That is, they are graded on the work they had done before class. The students need some coaching with how to use the felt tip pen, but they seem to dig it.

At the beginning of class, I usually write down all the problems that I’d like to see presented and then I ask for volunteers. In the case that more than one person wants to present a particular problem, the student with the fewest presentations has priority. If there is no priority, I try to choose one of the volunteers at random.

Depending on the number of problems and their difficulty, I will either have the students all come to the board at once to write down their solution while I bounce around the room answering questions or we’ll have one student come to the board at a time to present their proposed solution. In the first case, after the solutions are on the board, we will discuss each problem. In most cases, I’ll have the student that wrote down their proposed solution lead a discussion with the whole class about the problem and their solution.

Here is where my approach likely differs from many others. I don’t want all the solutions to be correct. I’d rather have students make mistakes. Ideally, I’d like to see a mixture of correct answers, answers with small mistakes, and answers with huge errors. It’s not that I want students to screw up. What I want is to have something to talk about. One of the greatest advantages of doing student presentations is that the audience should take on the role of skeptic. This makes the student engage with the material in a much different way than if they watch me. I’m an authority and usually the students just believe everything I say. I encourage the students to be willing to share what they have. It’s a low stakes endeavor for them. Just being willing to present is what they get credit for. (This is different in my upper-level proof-based courses.) On the other hand, I don’t want students to present total crap either.

This semester I have 48 students enrolled in calculus. I’d prefer a smaller class, but I can make it work. The goal is to get as many students to the board as possible. On Thursday, 9 students presented. I’m always concerned about how many students in class are engaged on presentation days. However, I’m confident that it is many orders of magnitude more than when I lecture (and I like lecturing and I think the students like it, too).

On Thursday, most of the solutions where flawless, but we also had a few that led to excellent discussions. In each of these cases, the presenters did a good job at fielding questions and comments from the audience and from me. This works because I make it a point to develop a community of trust. The audience has to behave appropriately. I encourage students to clap after each presenter and they clapped loudest after the two students that were at the board the longest due to flawed solutions. One of these students had told me before class that she did not understand function transformations (last week we were still reviewing precalculus). I encouraged her to volunteer for a problem related to function transformations, so that she could show us what we had. Indeed, she did have some misunderstanding, but in my view, this was the most beneficial presentation.