Saturday, November 27, 2010

Gaps in developmental math students' knowledge

The Pierce College Modular Math 115 project for a modular, self-paced, mastery-based elementary algebra course is in its third semester.

We've made adjustments each semester.  This semester we've used the open source online homework system WeBWorK so that students can verify that they have the correct answers on all the drill questions, so we no longer collect those homework sets on a daily basis.

This semester we are acknowledging how inadequately we have met the self-paced aspect of the plan.  The four sections of Modular Math 115 all meet at the same hour so that we can physically relocate students to the classroom that is progressing at the pace most appropriate for them.   In order to accommodate students who cannot master our elementary algebra materials within one semester, we are moving the slower students (electronically) to a course in the district database that covers only the first half of a two-semester elementary algebra course.

Among the 43 students in my classroom, none had mastered even two (of the nine total) units by the end of the twelfth week of fifteen weeks in the semester.

The students suffer all the mathematical gaps we have come to expect, such as inability to distinguish the concepts of area and perimeter.  But I was surprised by how many of the students have only a very shallow understanding of subtraction (and of course of multiplication and division).

They are all capable of computing 5 - 3.  And they can easily answer, "If you had 5 pencils and I took away 3, how many pencils would you still have?"

That particular word problem involves the simplest model for subtraction, "take away".  But my students have trouble with the more sophisticated, "If your pencil box holds 5 pencils and you already have 3, how many more pencils do you need to fill the pencil box?" 

The students do not automatically recognize their task as computing a difference.  Instead, they solve such a problem by counting up from 3, and so they have even more trouble with "If you had some pencils and then I gave you three more so that you had a total of 5 pencils, how many pencils did you have at the start?"

And they have more difficulty with a comparison question, "If you have 3 pencils and I have 5, how many more pencils do I have than you?"

Some of the students seems unfamiliar with the idea of multiplication as repeated addition--they know some multiplication facts but do not recognize that one can compute 3+3+3+3 by multiplying 4*3. 

Even if we assume that our students have access to technology to carry out computations and symbolic manipulations, some of these students do not recognize what calculation or manipulation is useful when given a context outside of pure mathematical computation.

Wednesday, October 27, 2010

Rope-stretching a right corner

A colleague asked today if one could find positive integers a, b, c, and d so that a2 + b2 + c2 = d2, or if that was an open problem.  He added that he'd heard that Egyptians stretched ropes to create 3-4-5 triangles in order to form right angles, and was wondering about the possibility of a three-dimensional analog.

I mentioned the Google Group investigating the harder problem of finding a rectangular box with integer sides, integer diagonals, and integer main diagonal.  (See

But only while driving home did it occur to me that it's straightforward to produce lots of examples of my colleague's easier problem.

Start with your favorite primitive Pythagorean triple (a, b, c).  (See my earlier post about Pythagorean triples:

Then c is odd, so c = 2n + 1, and

a2 + b2 + [2n(n + 1)]2 = [2n(n + 1) + 1]2

For example, 32 + 42 + 122 = 132.

Saturday, August 7, 2010

A short wish list for online homework systems

I take it for granted that electronic homework systems cannot effectively grade any math problem that requires students to write coherent sentences.

All the electronic homework systems allow the possibility of students submitting answers that won't be machine graded.  This capability greatly increases the variety of types of questions that can appear in an electronic exercise set.  There is an issue of how students enter math notation and figures (hey, just let them  photograph their handwritten answers with their cellphones and upload the jpg file), but the principal reason that I'm reluctant to include such problems is the fear that grading online will be cumbersome.

There are several ways to make life easier for the instructor faced with grading a single "essay" problem from a large set of students.  First, the interface for viewing individual responses should be intuitive and effortless.  Don't make us click on a link to open one student's response and then have to close that file before opening the next. 

It would be better to have "zoomable" thumbnails of each student's answers spread across the screen, with mouse flicks or dragging to scroll.  Should the instructor have the foresight to provide a grading rubric for the problem, that rubric should be visible (or at least available) to the student when working the problem.

In many cases, the availability of the rubric could reduce the instructor's need for to make copious comments.  For further convenience, the instructor should have a few editable paste buffers holding common comments (like "You need the product rule" or "This is not an equation").

Sunday, August 1, 2010

A joyful conspiracy

Uri Treisman's Joyful Conspiracy from CarnegieViews on Vimeo.

The Carnegie Foundation for the Advancement of Teaching is organizing a “joyful conspiracy” to help community colleges provide pathways to success for students who initially are placed in developmental mathematics courses.  The Statway will bring non-STEM students from the level of elementary algebra up to and through a transfer-level statistics course in one year.

The Statway 2010 Summer Institute brought teams from 19 community college campuses to the Stanford University campus July 25-30 to meet, share with, and learn from each other and from Carnegie Foundation leaders and consultants.  

We practiced the protocol for presenting, critiquing, and giving feedback on the lessons we will be piloting in the coming year.  Each lesson will involve students working on a rich task with clearly defined learning goals.  A key assumption of Statway is that statistics can provide a context for students to learn to think and reason quantitatively.  The necessary algebraic skills will be embedded within the lesson, rather than holding center stage.

Another core part of the instructional experience is that having students struggle with problems is desirable.  This student engagement, even when students do not discover or invent the necessary mathematics on their own, can be crucial to preparing the students for making sense of the central topic of the lesson.

Sunday, July 11, 2010

Statway lesson protocol

Thursday afternoon and Friday morning (July 8 – 9, 2010) Pierce College math faculty Vic LaForest, Bob Martinez, Kathy Yoshiwara, and I were in a “fishbowl” as part of the development of the Statway project.

In the coming year, faculty teams from 19 community college campuses will take materials (developed by the Carnegie Foundation for Advancement of Teaching) and create, test, analyze effectiveness of, and give feedback on statistics lessons. The purpose of our two-day experience was to test out a protocol developed for carrying out this process.

The lead facilitator was Bill Saunders, formerly of Pearson Learning Teams. He was joined by UCLA research colleagues Jim Stigler and Karen McGivven, Kris Bishop of the Dana Center (UT Austen), and Alicia Grunow of Carnegie.

We were not allowed to see the proto-lesson until we met Thursday. After a brief introduction to the protocol and the Statway lesson approaches, we four faculty members spent much of the afternoon working among ourselves deciding how we could best implement that lesson, while a video camera and the observers watched on.

We were expected to have the lesson design completed before our 5:30 pm adjournment Thursday. Bob was chosen to deliver the lesson at the start of the Friday session, and Karen volunteered to acquire the materials needed for our modified lesson. Kathy and I agreed to put together and email some of the materials Bob would need for his handouts.

Bob was working until 2:00 am putting together the materials.

Our Pierce College deans Jacquinita Rose and Crystal Kiekel were attending as guests. But when only 3 students showed up from the 8 students that had been recruited for Friday morning, we put Crystal and Alicia to work, enlisting them to act as students for Bob's lesson.

Bob did a great job running the lesson. After the students departed with their $20 iTunes gift cards, we continued the lesson protocol with the debriefing of how the lesson went, analyzing the student work, and writing feedback on the lesson.

The researchers were pleased with how everything went, and promised we would not be seeing the videos on YouTube.

Sunday, June 20, 2010

Variance in values from prediction by regression

In a section about linear regression in Understanding Statistics in the Behavioral Sciences (7th), Robert Pagano, Thomson, 2004, we find the following equation on page 119.

After an explanation of the notation, we find,
We could then construct for each score.  If we squared each and summed over all the scores, we would obtain

Obtaining this second equation from the first seems remarkable, but the textbook offered no insights on how one could see this.

Here's one possibility.

If we think of vectors , , and , then the second equation above is the assertion that

This equation is true whenever the vectors and are orthogonal.

But is precisely the orthogonal projection of onto the space spanned by and (see my earlier blog), so is in that space and is in the orthogonal complement.

Saturday, April 17, 2010

Statway: A pathway from developmental math through statistics

Los Angeles Pierce College has been invited to be one of sixteen community colleges to participate in the Carnegie Foundation's Statway project.

The key goal of the project is to provide a pathway for developmental math students to progress successfully from elementary algebra to completion of a transferable statistics course, all in one year.

The Statway project has already collaborated with AMS, ASA, MAA, AMATYC, NADE, NACME (National Action Council for Minorities in Engineering), and CAUSE (Consortium for the Advancement of Undergraduate Statistics Education).  Selected faculty from the professional mathematics societies make up the Carnegie Committee on Statistics Learning Outcomes, which has been working on identifying the core concepts, topics, and learning outcomes for transfer-level statistics.  The CCSLO is also identifying the developmental math learning outcomes needed to prepare students for learning statistics.

But in addition to redesigning the content and pathway to statistics, Statway will incorporate a student engagement component--roughly survival skills for a college student.

Monday, March 15, 2010

WeBWorK as an answer key

The principal author (Kathy Yoshiwara) of the project materials being used at Pierce believes that our  students misuse the answer keys found at the back of math textbooks.  She believes students need to struggle at times for an answer, rather than always be able simply to find the answers in the book (and to work backwards from there).

On the other hand, we recognize that students can benefit from the  reassurance of knowing that they've successfully solved a math exercise, or from the knowledge that their first efforts were in error.  As part of our student success projects for developmental math, we have been hiring student tutors to check off that students have correct answers before the students are allowed to submit their portfolios.

But we'd prefer that the tutors' time be spent in actually working with the students.  So we have begun to code answers to drill-type exercises into the open source online grading system WeBWorK.  Students will type in their answers online at home or in a computer lab, and will get immediate feedback as to whether or not their answers are correct.

We will still grade by hand the questions that require complete sentences as answers, and we will still  check the student work on the drill problems when we collect portfolios.  But students will now have a means of checking the accuracy of their answers before coming to the classroom and without needing to consult our tutors.

Wednesday, February 24, 2010

Removing students from a Moodle roster

Pierce College now creates an online course shell for each class of each instructor using Moodle, an open source Learning Management System.  The school automatically populates each Moodle course with students as they enroll in the corresponding real section.

However, the student remains enrolled in the Moodle course even after dropping (or being excluded) from the real course.

Removing a student from a Moodle course is non-intuitive.

First, click on "Assign roles" (in the Adminstration block).

Click on "Student" in the first column ("Roles").

Select the student from the left column (CTRL-click to select multiple students).
Click on the "Remove" button.

Wednesday, February 10, 2010


I've been using the open source homework system WeBWorK for the past few semesters.  The first couple of times, my classes were hosted by the University of Rochester (thanks to Michael Gage) and now by (thanks to Patrick McKeague).

The bank of problems in the WeBWorK National Problem Library is thin on the types of problems we want to use at Pierce College in our intermediate algebra class, so I've been authoring most of the problems.  The fact that all the authoring tools are made available to instructors is one of the nice features of WeBWorK, probably second only to the fact that it's free.

The downside is that without the huge work force associated with the big publisher-owned homework systems, the product is not so instructor-friendly.  We don't get all the bells and whistles that we might expect if we've only see the popular MyMathLab from Pearson.

I only just learned how to change a student's score on a graded assignment.  It goes like this:

  • Go to the Classlist Editor (the first link under Instructor Tools in the Main Menu).
  • In the row for the student of interest, click on the "Assigned Sets" value (in the fourth column--it has a form like  "m/n").
  • Click on the name of the appropriate set (in the "Edit set for..." column).
  • Find the problem of interest, and adjust the value of "status" (typically change "0" to "1") to give credit.

On the other hand, WeBWorK is (like the commercial product WebAssign) publisher-independent.  You could use it with a textbook from any publisher you use, or even (as with our program) if you are using materials that do not belong to any publisher.

The MAA is assuming the responsibility of maintaining WeBWorK ( from its original home at the University of Rochester.

Sunday, January 17, 2010

JMM 2010 (continued)

Further points of interest...

The MAA plans to undertake  a huge study of what's going on in college Calc I classes.  They hope to survey 25% of Calc I classes across the US.  Campuses not selected in the random sample will be given the opportunity to be take the survey to learn how they compare with the national sample, but their data will not be included in the national statistics.  (From David Bressoud, speaking at the department liaisons meeting)

States have called for Common Core State Standards (CCSS) for K-12 math and English.  The math group is being headed by Bill McCallum (U. Arizona).   For the first time ever (to my knowledge), "modeling" will occur as a separate topic/strand in a math standards document.  No working drafts have been made public, and public comment will evidently be limited to a few weeks in February 2010.  Although the initiative came from states, the feds will support it by tying Race to the Top funds to compliance with CCSS.  (AMS Committee on Education Panel Discussion, "The common core State Standards: Will they become our national K--12 math curriculum?")

Web 3.0 is the "Semantic Web"--searches  will not be simply over key words but key concepts.  The meaning of each item will be considered in the search.  For example, your search can include the word "red" to refer only to the color and to ignore the name "Red" and the meaning of "communist".  Or perhaps more enticingly, you can search for information about some algebraic expression (independent of Wolfram|Alpha).  (From Tom Leathrum, speaking at the MathDL advisory board meeting)

The Committee on Technologies in Mathematics Education (CTiME) submitted a proposal to sponsor (jointly with the Web SIGMAA) a panel session about the tablet pc and similar mobile stylus-type devices for the 2010 MathFest in Pittsburg.  This session will be dedicated in memory of Howard Penn, a long time CTiME member and supporter.  The committee will attempt to hold an online meeting during the spring 2010.  (Lang Moore, CTiME committee meeting)

Davide Cervone's newly unveiled MathJax looks like an exciting way to present math on the web.  It's still undergoing final tweaking.  (David Cervone speaking at a session of Publishing Math on the Web)  Davide's design also will  provide an improvement over programs like Beamer, which creates presentation slides with editable TeX-like math expressions.  (Mike Gage chatting between sessions)

The Committee on Two-Year Colleges (CTYC) voted to co-sponsor (with CRAFTY) a College Algebra contributed paper session for JMM 2011.  Rob Kimball talked about The Right Stuff, AMATYC's project about revamping college algebra.  AMATYC president Rob Farinelli spoke about AMATYC's Project ACCCESS (a professional development program newly hired in tenure-track position community college math positions) and rapidly developing work on a grant proposal involving the Hewlett Foundation and the Dana Center:  Mathway.  (CTiME committee meeting)

CRAFTY's  Curriculum Foundations II report (revamping college algebra)  is in production.  New committee chair Andy Bennett will investigate acquiring funds so that expenses could be paid to send  CRAFTY/Curriculum Foundation  II gurus to speak at MAA section meetings about best practices for a revised College Algebra.  (CRAFTY committee meeting)

CRAFTY's next big project will be to investigate the course commonly called "Precalculus."    The committee is providing the CBMS suggestions on possible questions for the next CBM survey.  (CRAFTY committee meeting)

The MAA's new VMware and servers will allow the MAA to host websites for all the MAA SIGMAAs and sections.  (John Wyatt, department liaison meeting)

Saturday, January 16, 2010

JMM 2010

I'm in my final day at the 2010 Joint Mathematics Meeting in San Francisco.

I attended a several committee meetings and sessions, but the most immediately interesting thing I learned was that Microsoft has a free program that converts freehand writing (using a tablet pc stylus) to typeset math expressions.

I googled "Microsoft equation writer" to find the download site and then downloaded and installed the pack that includes the equation writer.

My first trial worked fine.

But the next several attempts all gave unsatisfactory results.

I never did succeed in getting the program to recognize an upper case Delta, and I'm offended that it thought my handwritten "lim" looked like "sin" and that my "f(" looked like "lim"!

Fractions and radicals look ok, but the spacing is often poor, for example around the "="  or before the "dx" in a integral.


Friday, January 1, 2010

Solving quadratic equations via geometric construction

We can solve a quadratic equation of the form x2 - sx + p = 0, s, p \in \R, using the standard construction tools of compass and straightedge.  The method has been attributed to critic Thomas Carlyle.

Construct the circle in the Cartesian plane with center and passing through A(0,1).  By symmetry, the circle also passes through B(s, \, p) and C(0,p).

Circle in Cartesian plane

Because the circle has center   and passes through A(0,1), the equation of the circle is

\left( x-\frac{s}{2}\right)^2 +\left( y-\frac{p+1}{2}\right)^2 = \left( \frac{s}{2}\right)^2 +\left( \frac{p+1}{2}-1\right)^2

This reduces to

x2 - sxy2 - (p + 1)y + p = 0

So the x-intercepts of the circle are the solutions to  x2 - sx + p = 0.

Alternate justification:

The segment joining the x-intercepts has a length x_2 - x_1 = 2\left(\frac{s}{2} - x_1 \right), hence x1 + x2 = s.

Circle in Cartesian plane

\angle OCX_2 intercepts the arc AX1X2, and\angle AX_1X_2  intercepts the opposite arc, hence the two angles are supplementary.  But \angle AX_1 X_2 is also supplementary with \angle O X_1 A, so \angle OC X_2 is congruent to \angle OX_1 A, which in turn impies that  \triangle COX_2 \sim \triangle X_1 OA.  Hence


which implies that \frac{x_1}{1}=\frac{p}{x_2}, so x1 x2 = p.

Thus (xx1)(x - x2) = x2 - sx + p, and the solutions to x2 - sx + p = 0 are x1 and x2 .