Monday, September 22, 2008

Look for Solutions with Less Math and More Logic.

One instance where often “less is more.”

The following question is an excellent guideline for solving math word problems:
“How can I solve this problem by doing the least possible amount of math?”

Oftentimes there are several pathways from the setting of a problem to its final solution. Some routes are safer, while some are riskier, more error-prone. Some routes are faster, while some are time-consuming. Some routes are clearer, while some may be confusing.
Usually, the routes with more elementary operations (especially long division), and bigger numbers, tend to be lengthier, longer, and riskier, because adding, multiplying, and dividing big numbers or expressions requires a laser-focus attention. There are plenty of opportunities for doing silly mistakes during these calculations. Besides, it is easy to lose sight of the big picture when worrying about the accuracy of the calculations.
Factoring whole numbers and algebraic expressions is a good habit because it allows you to simplify some expressions before diving into the calculations, so you can operate with smaller numbers, gaining time, and accuracy.
Using logic is a very good habit, too. Many problems lend themselves to solutions that involve more reasoning, and less calculation. This is usually a good thing because these solutions tend to be clearer, and shorter.
Organizing all the information about a problem in a way that makes sense to you, is an excellent habit because this way you keep track of where you are and what you are doing all the time through the problem, and having all these references available makes it easy to retrace your steps, and identify any possible mistakes.
Go visual at any opportunity. Pictures, drawings, charts, graphs, and tables often are a huge help in writing down the right equations, or even in avoiding equations altogether sometimes.
There are many problems you can solve with a drawing and a little logic. Just because the problem is a math problem, that does not mean you need to write down an equation to solve it.
Focus on your possibilities, on what you can do. Organize the information in a logical way, using a drawing, or a table. Above all, try to spend the least possible amount of time and energy doing long, detailed, time-consuming calculations. Instead, simplify the expressions, and ask yourself logical questions about the problem.

Sunday, September 14, 2008

Missing Pieces of Information

Some search for doors, sometimes some do not want to see them

Last week I showed a student how to solve two linear equations in two unknowns. He knew perfectly well how to solve one equation with one variable but did not know how to combine two separate equations into one.
Also last week another student made the remark: “I do not know how to start solving this problem. What does ‘isoceles’ mean?” As soon as I gave him the definition of an isoceles triangle he successfully proceeded to solve the problem.
Earlier today another student asked me: “What is a frequency histogram?” When I explained the concept to him, he found it very clear. He said: “Just that? Documenting the numbers in a graph? That is pretty simple!”
Most times students take the initiative, and they spontaneously ask the meaning of terms they are not familiar with. Sometimes however, some students are near some sort of saturation point, and they do not want to even think about the remote possibility that maybe there is a concept they do not know, or a technique they have not seen, and they need this new information to solve the problem at hand. In these rare occasions they keep trying to solve the problem with only the insufficient tools they already have in their problem-solving toolkit.
Writer Kenneth Grahame said “The strongest human instinct is to impart information, the second strongest is to resist it.” So, I choose my words carefully when telling them there is something extra they absolutely need to know first before having any chance of solving the problem. Many times I let them finish their attempts, and check the solution in the back of the book so they realize their approach was wrong without me telling them so before hand, because that could increase their resistance.
There are several problem-solving techniques or approaches that seem indeed artificial, weird, or mystifying the first time around. Once you see how they work, and you use them a couple times, they become perfectly natural, and then you wonder why you never thought of that before.
A perfect example of this I saw also last week with another student.
It was a probability problem involving three coins. For me it is quite amazing to watch time and again how students keep trying to solve these problems by reasoning only about the three separate coins, as if the relevant probability space had only three points. The strong insistence in this naive approach is only matched in its consistency by the strong surprise students show the first time you show them the full eight-point probability space by branching out the development of the experiment at each successive flip, and recording the eight different combination triples. It is really interesting. Somehow these once missing pieces of information act like doors to a whole new realm of math knowledge when they are presented and opened. Many times the student’s reaction reminds me of that feeling of “Wow! I never thought that was a door!” I get when watching some sci-fi movies.

Thursday, September 11, 2008

Writing upside-down, and sideways

An indirect measure of tutoring experience

Last week, a student made this comment to me:
“Wow! You write not only upside-down but also sideways!”

Then I realized I have gradually acquired this ability over the years as a direct result of my continued math tutoring practice.

As a tutor, many times you have to correct a result, or an equation the student has just written. You are sitting across the table from them, and the correction may be a minor one. Reaching for their notebook across the table, grabbing it, turning it, putting it in front of you, writing what you want to write, and giving the notebook back to the student may not be extremely time consuming; however, the couple seconds it takes to move the notebook back and forth across the table may sometimes add up to something of a hassle if you find yourself having to make a lot of corrections and/or suggestions to keep the session moving forward.
In such cases, especially when the corrections are minor, once your hand is on the notebook at the other end of the table, it is much easier just to write whatever you have to write, right then and there, without ferrying the notebook to your side of the table.
For me the process started inadvertently, just by changing minus signs to pluses. From there it went on to changing y’s into x’s, inserting parenthesis, adding missing zeroes at the end of a number, and things like that. Still easy stuff but increasing in difficulty a little bit at a time.
The easiest digits to write upside-down are 0, 1, and 8. Before long, you can write all the digits upside-down. One day, all of a sudden you find yourself writing whole formulas upside-down. By this time, most likely you have started writing a few things also sideways, because often the student sits next to you but at a 90 degree angle.
I never had any independent practice writing upside-down or sideways on purpose. The only times I write sideways or upside-down are during my tutoring sessions. So I can say this ability, in my case, is a direct result, and therefore an indirect measure, of my tutoring experience.

Wednesday, September 03, 2008

Finding Problems That Motivate Students

Time units may help with multiplication practice

According to my experience each child is a unique learner. Generally speaking, students are more motivated to solve a particular problem when the problem relates to something they find real, meaningful, or important. However, different children usually assign different degrees of importance to the same thing. So it is always helpful to find a topic that holds a student’s interest, and that can be easily connected to math.
For example, let’s say you want to help a student who is struggling with multiplication tables. You can start a session by asking how many hours are there in a day, how many minutes in an hour, days in a week, and so on and so forth. Most third graders will know the answers off the top of their head. Then you proceed to ask how many minutes are there in a day, how many hours in a week, and so on and so forth. Children will realize these are multiplication problems but each child will react with a different degree of enthusiasm –or apathy– to find the answer.
Students who somehow have a strong connection to time units will diligently work out these multiplication problems all the way down to the number of seconds in a week. With a little bit of help they will continue working until they get all the numbers right, even if they struggle with the multiplications tables all along. They do this because they want to know the answers. In their mind, these problems are real, not just an empty drill.
Some other kids do not care at all how many seconds are there in a day, so for them this particular set of problems will not be very motivating. You will have to find a different set of problems for them.
Even when students understand the concept of multiplication, and the basic rules to multiply numbers, they may feel that some questions do not justify doing all the work necessary to find the answer. It depends on how real or important the questions seem to them, because that is what makes them want to find the answers.