Gary Rubinstein’s Blog: Math Topics That Need To Be Put Out of their Misery. Part 1: Writing Algebraic Expressions
Last month I wrote a post called ‘The Death of math’ which got a lot of attention as I described how I’d improve math teaching in this country by significantly reducing the number of topics taught and by making math optional after 8th grade. A line that got quoted a lot when people tweeted about this post was “If I were made ‘Math Czar’ I would gleefully chop at least forty percent of the topics that are currently taught from K to 12.”
The fact is that the original intent of the common core, was to address this very concern. The problem, though, is that they didn’t actually cut anything, as far as I can tell. Why this happened is tough to say. One complaint that teachers have about the common core is that they were developed by a very small group of people without input from teachers. Perhaps that small group didn’t have the heart to cut any topics.
Or maybe the committee, even if it was small, was unable to come to agreement on which topics should be cut. You see, the issue isn’t so much the size of the group or whether or not they got input from teachers, the issue is that the ability of that group wasn’t up to the task. Perhaps it would have been better if the task were left up to one very clever individual who understood the needs of teachers and of students and could be trusted to do this right. So, yes, I’m suggesting that rather than whatever group they formed, the common core standards would have been much better if they had just hired one person, namely me, to do the whole thing.
The first thing I would do if I were redesigning the math curriculum for this country would be to make a list of all the topics we teach and decide which can be cut. Over the years, topics just seem to get added and added to the curriculum, which is why math books are traditionally giant monstrosities. Rarely do you hear about anything being eliminated from the curriculum. I can think of only a few examples, like calculating square roots by hand, the log tables, and The law of tangents. All three of these topics, I think, were considered less important now that calculators have gotten so cheap. As I think about what needs to get cut, I’d, ironically, put two of those three topics back into the curriculum, but don’t worry, I’d cut way more than I’d add.
For a topic to be worthy of inclusion in a course of Mathematics, it must have at least one of the following three characteristics: 1) It must be thought provoking, 2) It must be beautiful, or 3) It must be useful. Percent problems, for example, are somewhat thought provoking, not very beautiful, but extremely useful so those would remain. Calculating Pi would be an example of something that is thought provoking and beautiful, but not particularly useful. Not many things would have all three properties, maybe teaching some types of encryption could come close. If a topic satisfies NONE of these three characteristics, it has no place in the math curriculum and must be ‘retired’ I think. Unfortunately many, if not most, of the topics we currently teach would fall into this category. I’m going to write a series of approximately ten posts in which I go into detail about some of these ‘stale’ topics, and why I think they can be safely eliminated and nobody will really miss them much.
You might wonder how it is that as a math teacher I find a way to teach some of these topics when I resent them so much. Well, for one thing, most of the classes I teach are for my ‘math research’ class where all the topics were chosen by me. But still, I teach ‘normal’ math too, and I suppose that I’m a bit like a musician in a wedding band when it comes to teaching topics that I don’t like very much. Surely musicians in wedding bands get pretty tired playing Earth, Wind, and Fire’s ‘September,’ yet when that song is requested they still play it as well as they can, giving it their own personal touch. So when I have to teach something, I still try to give it my best effort and find something thought-provoking in it to make it worthwhile. For some topics, this is not easy.
For the first topic on my list that I would love to cut from the math curriculum altogether is something that doesn’t even have an official name. Basically it is the skill of converting an Algebraic sentence from words into symbols, and looks like this from an actual modern textbook:
In case you’re wondering what the purpose of this topic is, it is for eventually solving algebra word problems that require manipulating variables on both sides of the equal sign. For instance: “In fifteen years, Mary will be twice as old as she was five years ago. How old is Mary now?” So this would get converted into the Algebra problem x+15=2(x-5), which becomes x+15=2x-10, which becomes x=25. So Mary is 25 years old now. Fifteen years from now she will be 40 years old which is twice as old as the 20 years old she was five years ago.
So you might think that I am opposed to contrived word problems like the question about Mary. Actually I don’t mind that question as some kind of riddle that students can apply things they have already learned for. But the process of spending a few days mastering the step where they convert sentences into symbols, so they can learn to do the age riddles in a mechanical mindless way is something that we have been torturing students with for too long.
Now the hope of the common core is that it would eliminate the requirement for mindless activity like this, but it is very clearly part of the sixth grade standards under 6.EE.A.2a:
CCSS.Math.Content.6.EE.A.2a Write expressions that record operations with numbers and with letters standing for numbers. For example, express the calculation “Subtract y from 5” as 5 – y.
Clearly, it is going to be a long time before students and teachers, alike, are rescued from this mind numbing topic. It doesn’t make kids smarter. It doesn’t make them ‘college or career ready.’ It just makes them want to get math over with as quickly as possible so they don’t have to think about it ever again.
Next time: Absolute value
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