# Tag Info

### Is there a virtue to learning how to compute by hand?

The following response is written with elementary-to-high-school mathematics in mind. A lack of a decent number sense really does encumber making sense of and parsing word problems, as well as the ...
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### Why do we introduce the notion that triangles are "congruent" instead of just saying that they are "the same" or "equal"?

Colloquially, there's a lot of conceptual overlap between all of these terms, but "sameness" is not a well-defined mathematical property. Congruent shapes need not be "the same" or ...

### Explaining why (or whether) zero and one are prime, composite or neither to younger children

"Because we said so" is a bit of a conversation closer, I agree. But "Because some people agreed a long time ago to define it that way so we could have conversations where we all understood each ...
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• 7,607

### Why do we introduce the notion that triangles are "congruent" instead of just saying that they are "the same" or "equal"?

The smart-aleck answer is that most congruent triangles, or congruent figures more generally, aren't actually "the same" or "equal". Usually when we say two things are "the ...

### Is there a virtue to learning how to compute by hand?

I find the ability to estimate calculations quite useful and I think you need to be able do do calculations to estimate them. If you are keeping a grocery budget, I would suggest you should know what ...

### Is there a virtue to learning how to compute by hand?

Yes! But the virtue doesn't lie in being able to do the calculation but in gaining a feel for numbers as well as algorithmic thinking. I teach Computer Science freshmen and one of the first things we ...
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### Is there a virtue to learning how to compute by hand?

I taught at the elementary and high school levels. At times we used calculators and at times we didn't. Students benefit from experience both ways. Students need to learn that calculators are only a ...
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### What is the preferred way to denote the Pythagorean theorem equation?

Common knowledge The formula $a^2+b^2 = c^2$ is common knowledge and the words for hypotenuse and leg (is "cathetus" not used in English?) are basic mathematical vocabulary. Including these ...
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### What value is there in requiring students to declare the dimensions of an answer when it is already clear from context?

In my experience with remedial-level community-college students (USA), it is simply never the case that the units are trivially "clear from context". I can easily see some of my former ...
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### Prisoner's dilemma formulation for children

Here's a silly example: Give students collections of the same type of thing, where each collection contains "good" objects and "bad" objects -- for example, a stack of Pokemon cards with both rare ...
• 9,729

### What kind of sequence is between an arithmetic and a geometric sequence?

Polynomials with $\textrm{degree}>1$ grow faster than arithmetic sequences but slower than geometric sequences. More generally, after sufficiently many terms: \begin{align*} & \textrm{logarithm}...
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### Prisoner's dilemma formulation for children

I found out about the Prisoners' Dilemma as a kid from a book about the Harry Potter phenomenon, which had a chapter about the problem, but presented as a story about Harry and Draco being accused of ...
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### What kind of sequence is between an arithmetic and a geometric sequence?

The hidden connection between arithmetic and geometric sequences If we stack circles on the function $y=|x|^\color{red}{1}$, the sequence of radii is geometric. (proof) If we stack circles on the ...
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### How to Write Steps of Solving Equations?

I wouldn't do that. The parenthesis in use are also used for legal expressions within equations. So you can end with one line containing the same parenthesis meaning different things, what looks like ...
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### Is there a virtue to learning how to compute by hand?

I attended the Computer based math educational summit back in 2016 and found their ideas interesting. I agree with some of their points and disagree with others, but it is certainly interesting to ...
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### Do any middle-school texts indicate that irrationality requires proof?

Here's a quote from the syllabus for the 9th grade in the school type "Gymnasium" in the federal state of Bavaria in Germany: Kompetenzerwartungen und Inhalte Die SchÃ¼lerinnen und SchÃ¼ler [....
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### Is there an agreed upon difference between how we represent $\frac{a}{b}$ and $a \cdot \frac{1}{b}$?

The common core state standards definition of the fraction $\frac{N}{D}$ of a unit is to subdivide the unit into $D$ equal sized pieces. Each of these pieces is defined to be $\frac{1}{D}$ of the ...
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### What value is there in requiring students to declare the dimensions of an answer when it is already clear from context?

The legitimate purpose of this is trying to get the student to actually read the question and take note of the fact that there is indeed a context. Many students approach mathematical exercises as &...
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### How to Write Steps of Solving Equations?

Speaking as someone who has taught college precalculus several times, I have an intense dislike for the way that Geogebra writes this step. In my opinion, it is very important to emphasize to ...
• 345

### How to Write Steps of Solving Equations?

The problem with $(4x+7=6x+2)-6x$ is that there is no subtraction operation that involves subtracting a term from an equation. Subtraction involves subtracting a term from a term. So the correct ...
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### Explaining why (or whether) zero and one are prime, composite or neither to younger children

FYI: here's some pro and con: http://primefan.tripod.com/Prime1ProCon.html One was originally considered prime. It is prime with the most convenient ("natural") definition. It got excluded from ...
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### Is there a virtue to learning how to compute by hand?

I have thought a lot about this question since posting it, and having read the other answers and the many comments, I want to add a perspective that no one else seems to have given. Most of the real ...
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### What is the preferred way to denote the Pythagorean theorem equation?

In Olympiad geometry, $a$, $b$, $c$ is the so-called standard notation for the sides of a triangle, so it makes sense to use it consistently when referring to a triangle (in isolation). However, in ...
Accepted

### Do any middle-school texts indicate that irrationality requires proof?

Here are two typical examples in print and digital educational content of how this is done: From Open-Up Resources: In your future studies, you may have opportunities to understand or write a proof ...

### Patterns that unexpectedly fall apart at large $n$

It might work better, with this age level, not to be concerned about how large n is when the apparent pattern falls apart. My favorite example is the problem of making all possible straight-line ...
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### Patterns that unexpectedly fall apart at large $n$

I second Sue Van Hattum's suggestion that you should not be so concerned with how large the $n$ is where the pattern eventually fails. I'll go one step further and recommend an example where that $n$ ...
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### Is there a virtue to learning how to compute by hand?

Brian D. Rude, "The Case For Long Division." 2004. HTML link. This is a somewhat long (unpublished) article (which I haven't studied carefully), but maybe the excerpt below suffices to give ...