Posted in Curriculum Reform, Mathematics education

Teaching through Problem Solving

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Problem solving is not only the reason for teaching and learning mathematics. It is also the means for learning it. In the words of Hiebert et al:

Students should be allowed to make the subject problematic. … Allowing the subject to be problematic means allowing students to wonder why things are, to inquire, to search for solutions, and to resolve incongruities. It means that both curriculum and instruction should begin with problems, dilemmas, and questions for students. (Hiebert, et al, 1996, p. 12)

For years now, UP NISMED in-service training programs for teachers have organized mathematics lessons for teachers using the strategy we call Teaching through Problem Solving (TtPS). This teaching strategy had also been tried by teachers in their classes and the results far outweighed the disadvantages anticipated by the teachers.

Teaching through problem solving provides context for reviewing previously learned concepts and linking it to the new concepts to be learned. It provides context for students to experience working with the new concepts before they are formally defined and manipulated procedurally, thus making definitions and procedures meaningful to them.

What are the characteristics of a TtPS?

  1. main learning activity is problem solving
  2. concepts are learned in the context of solving a problem
  3. students think about math ideas without having the ideas pre-explained
  4. students solve problems without the teacher showing a solution to a similar problem first

What is the typical lesson sequence organized around TtPS?

  1. An which can be solved in many ways is posed to the class.
  2. Students initially work on the problem on their own then join a group to share their solutions and find other ways of solving the problem. (Role of teacher is to encourage pupils to try many possible solutions with minimum hints)
  3. Students studies/evaluates solutions. (Teacher ask learners questions like “Which solutions do you like most? Why?”)
  4. Teacher asks questions to help students make connections among concepts
  5. Teacher/students extend the problem.

What are the theoretical underpinnings of TtPS strategy?

  1. Constructivism
  2. Vygotsky’s Zone of Proximal Development (ZPD)

Click here for sample lesson using Teaching through Problem Solving to teach the tangent ratio/function.

The best resource for improving one’s problem solving skills is still these books by George Polya.

How to Solve It: A New Aspect of Mathematical Method (Princeton Science Library)

Mathematical Discovery on Understanding, Learning, and Teaching Problem Solving, Volume I

Posted in What is mathematics

The heart of mathematics

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Axioms, theorems, proofs, definitions, methods, are just some of the sacred words in mathematics. These words command respect and create awe  especially to mathematicians but deliver shock to many students. P.R. Halmos argued that not even one of these sacred words is the heart of mathematics. Then, what is? Problem solving. Solving problems is at the heart of mathematics.


Indeed, can you imagine mathematics without problem solving? It might as well be dead! But why is it that problem solving tasks are relegated as end of lesson activity? When it’s almost end of the term and the teacher’s in a hurry to finish their budget of work, the first to go are the problem solving activities. And when time allows the teacher to engage students in problems solving, the typical teaching sequence goes like this based on my observation in many math classes and from the teaching plans made by teachers.

  1. Teacher reviews the computational procedures needed to solve the problem.
  2. Teacher solves a sample problem first usually very neatly and algebraically (especially in high school)
  3. Teacher asks the class to solve a similar problem using the teacher’s solution
  4. Students practice solving problems using the teacher’s method.

Even textbooks are organized this way!In this strategy, students are given problem solving tasks only after having learned all the concepts and skills needed to solve the problem. Most often than not, they are also shown a sample method for solving the problem before they are given a set of similar problems to work on. I will not even call this a problem solving activity/lesson. How can a problem be a problem if you already know how to solve it? Of course, this particular strategy also gives the students the opportunity to deepen, consolidate and synthesize the new math concepts they just learned. But it also deprives them the opportunity to engage in real problem solving where they themselves figure out methods for solving the problem and using knowledge they already possess.

Another approach to increase students engagement with problem solving is to teach mathematics through problem solving.

Posted in Trigonometry

Trigonometry – why study triangles

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Why study trigonometry?

We study Trigonometry because it is useful. Its earliest and simplest use is to find the missing part of a triangle. But mathematicians do not just study something because it is useful. More often, they study something because it is fascinating. This fascination with triangles especially in the measure of it sides and angles has developed into a coherent piece of mathematical knowledge we now call trigonometry.

Why not quadrinometry?

What is so special about triangles? Why did mathematicians created a branch of mathematics devoted to the study of it? Why not quadrinometry? Quadrilaterals, by its variety are far more interesting. Not only that, each piece of shape is related to another piece. If you know quadrilateral, you’ll know about the rest of the quadrilaterals. But this is also precisely the reason why we study trigonometry, why we study triangles. If you know it, you’ll know about any polygon not just quadrilaterals. Any polygon can be dissected into pieces of triangles! Try dissecting any of these shapes:

What’s with right triangles?

There are different kinds or shapes of triangles. In terms of angles we have equiangular, acute, obtuse, and right triangles. Why is it that we devote so much time studying about right triangles in trigonometry? Try dissecting the other triangles and you’ll know why if you know about right triangles, you’ll know about the other triangles!.

 

 

 

 

 

 

 

 

 

 

 

Here’s a bonus reason: when you study triangles, you don’t need to deal with nonconvex ones!
Click Teaching trigonometry through problem solving for a sample lesson on teaching trigonometry in presentation format.

I created a worksheet for the activities on classifying and dissecting polygons. Click the link.

Posted in Math investigations

Exercises, Problems, and Math Investigations

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The quality of mathematics students learn depends on the mathematical tasks or activities we let our students engage in.

Mathematical activities/tasks can be categorized into three types: exercises, problem solving, and math investigations.

Standard exercises

These are activities with clearly defined procedure/strategy and goal. Standard exercises are used for mastery of a newly learned skill – computational, use of an instrument, and even new terms or vocabulary. These are important learning activities but must be used in moderation. If our teaching is dominated by these activities, students will begin to think mathematics is about learning facts and procedures only. This is very dangerous.

Problem solving activity

These are activities involving clearly defined goals but the solutions or strategies are not readily apparent. The student makes decision on the latter. If the students already know how to solve the problem then it is no longer a problem. It is an exercise. Click here for features of good problem solving tasks. It is said that problem solving is at the heart of mathematics. Can you imagine mathematics without problem solving?

Math investigations

These are activities that involve exploration of open-ended mathematical situation. The student is free to choose what aspects of the situation he or she would like to do and how to do it. The students pose their own problem to solve and extend it to a directions they want to pursue. In this activity, students experience how mathematicians work and how to conduct a mathematical research. I know there are some parents and teachers who don’t like math investigation. Here are some few reason why we need to let our students to go through it.

  1. Students develop questions, approaches, and results, that are, at least for them, original products
  2. Students use the same general methods used by research mathematicians. They work through cycles of data-gathering, visualization, abstraction, conjecturing and proof.
  3. It gives students the opportunity communicate mathematically: describing their thinking, writing definitions and conjectures, using symbols, justifying their conclusions, and writing and reading mathematics.
  4. When the research involves a class or group, it becomes a ‘community of mathematicians’ sharing and building on each other’s questions, conjectures and theorems.

Students need to be exposed to all these type of mathematical activities. It is unfortunate that  textbooks and  many mathematics classes are dominated by exercises rather than problem solving and investigations tasks, creating the misconception that mathematics is about mastering skills and following procedures and not a way of thinking and communicating.

Samples of these tasks are shown in the picture below:

Click here and here for a sample teaching using math investigation.