Posted in Teaching mathematics

What is variation theory of learning?

variation theoryVariation theory of learning was developed by Ference Marton of the University of Gothenburg. One of its basic tenets is that learning is always directed at something – the object of learning (phenomenon, object, skills, or certain aspects of reality) and that learning must result in a qualitative change in the way of seeing this “something” (Ling & Marton, 2011). Variation theory sees learning as the ability to discern different features or aspects of what is being learned. It postulates that the conception one forms about something or how something is understood is related to the aspects of the object one notices and focuses on.

Here’s an example: In linear equations you want your students to learn that a linear equation in one unknown can only have one root while an equation with two unknowns can have infinitely many roots.  You also want them to learn that in an equation of one unknown, the root is represented by x only while in equation with two unknowns, the root is represented by an ordered pair of x and y. It is also important that students will see that while both roots can be represented by a point, the root of the equation in one unknown can be plotted in a number line or one-dimensional axis while the root of the equation in two unknowns are plotted in two-dimensional coordinate axes. Will the students discern these particular differences between the roots of the two types of equation in the natural course of teaching linear equations or should you so design the lesson so that students will focus on these differences? Variation theory tells you, yes, you should.

At the World Association of Lesson Studies (WALS) conference in HongKong in 2010 most of the lesson studies presented were informed by variation theory. The teachers reported that students achievement showed significant increases in the post test. Everybody seemed to be happy about it. I think it is not only because of its effect on achievement but it also gave the teachers a framework for structuring their lesson particularly on the design and sequencing of tasks. This sounds very simple but it is actually challenging. The challenge is in identifying the critical feature for a particular object of learning – what is it they need to vary and what needs to remain invariant in the students experiences. Variation theory asserts that change in conception can occur by highlighting critical elements of the object of learning and creating variation in these while all other elements are held constant.

Variation theory directs the teacher to focus on the critical aspect of the object of learning (a math concept, for example), identify differing level of conceptions, and from each of these conceptions identify the critical elements (core ideas) which needed to be varied and those that will remain invariant. In mathematics, these invariants are usually the properties of the concept. In the case of the angles for example, in order for students to have a ‘full’ understanding of this concept they needed to experience it in different forms – the two-line angles, the one-line angles, and the no-line angles.

teaching angles
‘Types’ of Angles

What they need to learn (abstract) from these is that they all consist of two linear parts (even if they are not visible) and they cross or meet at a point and that the relative inclination of the two parts has some significance – it defines the sharpness of the corner or the their openness. Given these, the teacher now has to design the lesson/ tasks that will provide the necessary variation of learning experiences. You can read my post Angles aren’t that Easy to See for further explanation about understanding angles. Check also my post on how to select and sequence examples to see how variation theory is useful for thinking about examples.

Teachers must always remember however that “even if they aware of the need for the appropriate pattern of variation and invariance, quite a bit of ingenuity may be required to bring it about. Providing the necessary conditions for learning does not guarantee that learning will take place. It is the students’ experience of the conditions that matters. Some students will learn even though the necessary conditions are not provided in class. This may be because such conditions were available in the students’ past, and some students are able to recall these experiences to provide a contrast with what they experience in class. But, as teachers we should not leave learning to happen by chance, and we should strive to provide the necessary conditions to the extent that we are able” (Ling & Marton, 2011). I think we should also remember that the way the learners are engaged is a big factor in learning. You may have addressed the critical feature through examples with appropriate pattern of variation but if this was done by telling, learning may still be limited and superficial.

Another useful guide for effecting learning is creating cognitive conflict. Click Using cognitive conflict to teach solving inequalities to see a sample lesson.

Posted in Geometry

Guest Post: Real World Uses of Geometry

“When am I going to use this?” This question has been asked in almost every geometry class at one point or another. Many students introduced to advanced mathematics, such as geometry and trigonometry, will deem it worthless. This could not be further from the truth. There are many real world uses for geometry and many careers that require a functional knowledge of it to be successful. If you are currently studying geometry and finding it difficult, consider hiring a professional geometry tutor to assist you in your studies. Also reach out to your teachers and other students to ensure you leave your geometry class with a solid understanding. Using geometry is an essential skill to master.

Every Day Uses of Geometry

Geometry is used throughout many areas of daily life, even if it is not required by your career. John Oprea, author of the book Geometry in the Real World, discusses how many areas of life can benefit from the use of geometry. Below are a few examples of uses of geometry almost everyone will encounter throughout their lives.

  • Lawn Care – When you purchase fertilizer or grass seeds, you may notice that the bags are listed with a square foot measurement. To properly purchase the correct amount of seed or fertilizer, you will need to determine the square footage of your lawn. Without doing some quick geometry you may not purchase enough, or waste money purchasing too much.
  • Purchasing Items – Have you ever moved into a new residence and had the task of filling it with furniture and appliances? Even the seemingly simple task of determining the best use of your area can benefit from basic geometry. How much area will the recliner occupy? Is there room for the seven sectional couches?  Geometric calculations can answer these questions. Purchasing certain appliances also requires geometry. Freezers and refrigerators list their storage capacity in cubic feet. By understanding what a cubic foot means, and calculating an estimate of your household storage needs, you can purchase an appliance that will accurately address your requirements.
  • Household Repairs – A variety of different household repairs can benefit greatly from running some quick geometric equations. Repairing your roof will require you to determine the square footage so you can purchase the appropriate amount of shingles. Any sort of repair involving carpentry will require geometry. You must ensure the corners are perfectly square and the walls are plumb. Geometry will help you determine the design of a new project and how much material you will need.
Careers That Require Geometry

Hundreds of careers require an expert level understanding of geometry in order to be successful. David Eppstein, author of Geometry in Action and writer for the University of California Irvine, states the below careers are heavily involved with geometry.

  • Architecture – From the Pyramids in Egypt to the skyscrapers of New York, geometry is the building block of architecture. Before the ground is broke and foundation is laid, an architect will draft a complete model of the new building. The architect’s primary focus when designing a building is using geometry to create a safe structure. Every angle, and the length of every side, is carefully calculated in accordance with geometric principles to create a structure that can safely withstand the elements and any other hazards it may encounter.
  • Computer Graphics Artist – This modern field of artistry and design merges almost every aspect of geometry in a computer simulation to create a variety of graphics. Cutting edge software allows graphic artists to create visually compelling and aesthetically pleasing graphics that are used in video games, movies and presentations. While the computer is able to handle a lot of the behind the scenes math, a solid understanding of geometry is required to be able to construct the complex models artists create.
  • Video Engineering – How do projectors create a crisp compelling image that fills up the screen? How do directors determine which lens to use for their ideal shots? They employ video engineers to solve these problems. Using their mathematic prowess, they are able to calculate which lens will create the optimal field of view the director is requesting. They also determine the perfect location to setup the projector and the best angle to produce a clear and crisp image on the screen.
Geometry: Well worth Learning

The examples above are only a small sampling of the uses of geometry. It is used every day in a variety of careers and tasks. Applying yourself fully to your geometric studies can prepare you for your ideal career and help solve many problems you may encounter throughout life.
About the Author:

Andrew Boyd is a writer who has enjoyed geometry since he was introduced at an early age. As a hobby carpenter, he uses geometry on a daily basis and loves showing others why it’s such a worthwhile field of study.

Recommended readings:
Fostering Geometric Thinking: A Guide for Teachers, Grades 5-10
Understanding Geometry for a Changing World: NCTM’s 71st Yearbook

Posted in Algebra

Strengths and limitations of each representation of function

Function is defined in many textbooks as a correspondence between two sets x  and y such that for every x there corresponds a unique y. Of course there are other definition. You can check my post on the evolution of the definition of function. Knowing the definition of a concept however does not guarantee understanding the concept. As Kaput argued, “There are no absolute meanings for the mathematical word function, but rather a whole web of meanings woven out of the many physical and mental representations of functions and correspondences among representations” (Kaput 1989, p. 168). Understanding of function therefore may be done in terms of understanding of its representations. Of course it doesn’t follow that facility with the representation implies an understanding of the concept it represents. There are at least three representational systems used to study function in secondary schools. Kaput described the strengths and limitations of each of these representational systems. This is summarised below:

Tables: displays discrete, finite samples; displays information in more specific quantitative terms; changes in the values of variables are relatively explicitly available by reading horizontally or vertically when terms are arranged in order (this is not easily inferred from graph and formula).

Graphs: can display both discrete, finite samples as well as continuous infinite samples; quantities involved are automatically ordered compared to tables; condenses pairs of numbers into single points; consolidates a functional relationship into a single visual entity (while the formula also expresses the relationship into a single set of symbols, individual pair of values are not easily available for considerations unlike in the graph).

Formulas/ Equations: a shorthand rule, which can generate pairs of values (this is not easily inferred from tables and graphs); has a feature (the coefficient of x) that conveys conceptual knowledge about the constancy of the relationship across allowable values of x and y — a constancy inferable from table only if the terms are ordered and includes a full interval of integers in the x column; parameters in equation aid the modelling process since it provides explicit conceptual entities to reason with (e.g. in y = mx, m represents rate).

It is obvious that the strength of one representation is the limitation of another. A sound understanding of function therefore should include the ability to work with the different representations confidently. Furthermore, because these representations can signify the same concept, understanding of function requires being able to see the connections between the different representations since “the cognitive linking of representations creates a whole that is more than the sum of its parts” (Kaput, 1989, p. 179). Below is a sample task for assessing understanding of the link between graphs and tables. Click solutions to view sample students responses.

tables and graphs

How do you teach function? Which representation do you present first and why?

Reference

Ronda, E. (2005). A Framework of Growth Points in Students Developing Understanding of Function. Unpublished doctoral dissertation. Australian Catholic University, Melbourne, Australia.

Posted in Mathematics education

NCTM Process Standards vs CCSS Mathematical Practices

The NCTM process standards, Adding it Up mathematical proficiency strands, and Common Core State Standards for mathematical practices are all saying the same thing but why do I get the feeling that the Mathematical Practices Standards is out to get the math teachers.

The NCTM’s process standards of problem solving, reasoning and proof, communication, representation, and connections describe for me the nature of mathematics. They are not easy to understand especially when you think that school mathematics is about stuffing students with knowledge of content of mathematics. But, over time you find yourselves slowly shifting towards structuring your teaching in a way that students will understand and appreciate the nature of mathematics.

The five strands of proficiency were also a great help to me as a teacher/ teacher-trainer because it gave me the vocabulary to describe what is important to focus on in teaching mathematics.

With the Mathematical Practices Standards I had this picture of myself in the classroom with a checklist of the standards in one hand and a lens on the other looking for evidence of proficiency. The NCTM and Adding it Up standards actually said more about math. The ones in Common Core are saying more about what students should attain. I wonder which will encourage ‘teaching to the test’. The day teachers start to ‘teach to the test’ is the beginning of the end of any education reform.

NCTM Process Standards

Five Strands of Mathematical Proficiency

CCSS Mathematical Practices

Problem Solving

  1. Build new mathematical knowledge through open-ended questions and more-extended exploration;
  2. Allow students to recognize and choose a variety of appropriate strategies to solve problems;
  3. Allow students to reflect on their own and other strategies for solving problems.

Reasoning and Proof

  1. Recognize and create conjectures based on patterns they observe;
  2. Investigate math conjectures and prove that in all cases they are true or that one counterexample shows that it is not true;
  3. Explain and justify their solutions.

Communication:

  1. Organize and consolidate their mathematical thinking in written and verbal communication;
  2. Communicate their mathematical thinking clearly to peers, teachers, and others;
  3. Use mathematical vocabulary to express mathematical ideas precisely.

Connections

  1. Understand that mathematical ideas are interconnected and that they build and support each other;
  2. Recognize and apply connections to other contents;
  3. Solve real world problems with mathematical connections.

Representation

  1. Emphasize a variety of mathematical representations including written descriptions, diagrams, equations, graphs, pictures, and tables;
  2. Select, apply, and translate among mathematical representations to solve problems;
  3. Use mathematics to model real-life problem situations.

Conceptual Understanding refers to the “integrated and functional grasp of mathematical ideas”, which “enables them [students]
to learn new ideas by connecting those ideas to what they already know.”

Procedural fluency is defined as the skill in carrying out procedures flexibly, accurately, efficiently, and
appropriately.

Strategic competence is the ability to formulate, represent, and solve mathematical problems.

Adaptive reasoning is the capacity for logical thought, reflection, explanation, and justification.

Productive disposition is the
inclination to see mathematics as sensible, useful, and worthwhile, coupled with a belief in diligence and one’s own efficacy.

Mathematically proficient students …

  • Make sense of problems and persevere in solving them.
  • Reason abstractly and quantitatively.
  • Construct viable arguments and critique the reasoning of others.
  • Model with mathematics.
  • Use appropriate tools strategically.
  • Attend to precision.
  • Look for and make use of structure.
  • Look for and express regularity in repeated reasoning.

Image from 123RF