Dirk
  • Member for 7 years, 2 months
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How do I nicely tell my coworkers that they are NOT mathematicians?
37 votes

I do not know if there is an accepted definition of what a mathematician is. There are teachers of mathematics and professors of mathematics, for example, and most people agree that people of the ...

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Why do we teach even and odd functions?
16 votes

Besides applicability in topics like integration and Fourier analysis, it also connects algebra to calculus at least in the way that multiplication of even/odd functions behaves like addition even/odd ...

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is it appropriate or beneficial to mention weird results in math?
Accepted answer
12 votes

I would be careful with the type of result for which one needs a lot of new math to digest the explanation. For example, I would avoid talking about $ 1 + 2+3+.. = -1/12$ because there is basically ...

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Good examples of functions defined as definite integrals of elementary functions?
12 votes

My first take is $$ \ln(x) = \int_1^x\frac1t dt. $$ Granted, some texts introduce the natural log of the inverse of $\exp$ but other texts define $\ln$ as above and the $\exp$ as the inverse. If I ...

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Why is it possible to teach real numbers before even rigorously defining them?
11 votes

At German universities, one of the first lectures in mathematics is "Analysis 1" which is a kind of "rigorous calculus" and there one always proceeds more or less like this: We start with an ...

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A Method to Grade a Multiple Statement or True and False Question
11 votes

For multiple choice questions it is much better to ask in a slightly different way, namely Are the following numbers even? yes no 1.) O O 17 2.) O O 22 3.) O O 33 4.) O O ...

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Students' Messy Sheets: The Big Problem of Exams and Homeworks
11 votes

Besides mastering the material in the course one thing that the students have to learn during studies is to communicate mathematics in written form. Almost nobody comes to university and is able to ...

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Examples of vocabulary that have different meanings in Mathematics compared to "everyday" English
10 votes

This can get quite some list… Here are a few: function: a mapping in mathematics vs. a "feature" a "purpose" and "functionality" in everyday language root: e.g. a point where a function is zero vs. ...

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Real-world examples of more "obscure" geometric figures
10 votes

So called tensile structures in architectures are indeed minimal surfaces. Popular examples are the Olympiastadium in Munich: or the former Millenium Dome in London:

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What is the intuition behind the limit superior?
Accepted answer
9 votes

I have two intuitions to offer: A sequence $(a_n)$ may have cluster points (these are points such that every neighborhood contains infinitely many elements of the sequence, or, more precisely, for ...

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Examples of Mathematical Slang
8 votes

If you simplify a term by adding and subtracting something you call this a "nahrhafte Null" in German (probably translates to "nutritious null"?).

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What are your favorite instructional counterexamples on sequences?
8 votes

My favorite counterexample is one about exchange of limits: $$a_{n, m} =\frac{n}{n+m}. $$ It is indeed pretty simple to see that $\lim_{n\to\infty} \lim_{m\to\infty}a_{n, m} \neq \lim_{m\to\infty} \...

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Why do we teach estimation in Statistics and Mathematics?
7 votes

I'd say a good approximation is often better that an exact result. This may sound counterintuitive, but as the phrase is vague anyway, here is a longer explanation what I mean: An "exact result&...

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How can I convince students that Fourier series are useful?
7 votes

There are tons of reasons: Signal theory: The key phrase here is bandwidth. If you want to transmit a signal over an analog channel you could modulate it onto a carrier frequency. To ensure that you ...

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How can I discourage proof by patchwork?
7 votes

I think the situation is tricky. Without knowing more about the actual problem it may well be that this proof by patchwork will be finished after a few iterations. This happens when every ...

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Proper ordering of phrase "multiplied by"
6 votes

Drawing an analogy to the multiplication of matrices (where order does matter): If I read "$A$ multiplied by $B$" I would probably think of $AB$ first, but probably I would realize that ...

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Why is multivariable analysis often omitted?
Accepted answer
6 votes

$\newcommand{\RR}{\mathbb{R}}$I am not really sure if I understood your question correctly, especially if we have the same understanding of what "multivariable calculus" is. If by multivariable ...

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References for graduate education
4 votes

As far as I remember Krantz's book How to Teach Mathematics is not restricted to undergraduate courses and contains a lot of great advice. His book A Mathematician Comes of Age is not focused on ...

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Examples of Mathematical Slang
4 votes

What is called "fórmula del chicharronero" in Central Mexico (see the answer by Rodrigo Zepeda) is called "Mitternachtsformel" ("midnight formula") in middle school in some parts of Germany. This is ...

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Use of mathematical humor suitable for motivation/explaination?
4 votes

I think one important distinction is: Is the joke about mathematics or about mathematicians? An example of the former is the "rat poison principle" from Steve Gubkin's comment or any other "funny ...

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Teaching students to write the "invisible" ones
4 votes

Actually, I don't think that it is quite right that there really "is an invisible $-1$" in front of $-x$. I would say that one defines the symbol $-x$ to be the one that fulfills $x + (-x) = 0$ and ...

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Is Applied Math easier than Pure Math?
4 votes

My two cents are: There is not a real dividing line between "pure" and "applied" mathematics. I think the real distinction is between mathematicians (or "want-to-be-mathematicians") who are inspired ...

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Gauging correspondence between classtime and material rate
Accepted answer
3 votes

I also tried to estimate this for my lectures in advance for some years but couldn't really figure it out. However, after a several years of teaching math I got pretty good at estimating. Here is what ...

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Ideas for teaching a bit of linear optimization to advanced undergraduates?
3 votes

I have not tried anything similar myself, but if I had to, I would start by looking at Gilbert Strang's book "Introduction to applied mathematics" in chapter 8 "Optimization" (8.1 is "Introduction to ...

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Transitioning from 'Read textbook to learn' to 'Read original paper/Read paragraphs of textbooks'
2 votes

I'd say that it is not "linearly" vs. "nonlinearly" or "whole book" vs. "paragraphs" but rather you should change your focus when starting to read. When you transition to research, you should not ...

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How can I implement the principles of deliberate practise in my mathematical studies?
2 votes

I haven't heard of deliberate practice before but what you describe sounds pretty much like what we do in math courses at the university where I am (and also at most others in Germany): We give ...

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How to motivate the surface element
2 votes

$\newcommand{\RR}{\mathbb{R}}\renewcommand{\span}{\mathrm{span}} \newcommand{\vol}{\mathrm{vol}}$ Here is my own answer: Let's assume that you know that the volume of an $n$-dimensional ...

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How to teach binary numbers to 5th graders?
2 votes

I haven't tried this in a class but it worked in one-on-one conversation with kids at basically all ages (well, ability to count is needed but that's basically it). It also has the benefit, that you ...

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Why is the concept of injective functions difficult for my students?
1 votes

I find the view of solving equations very helpful, when I explain injective and surjective functions: A function $f:X\to Y$ is injective if the equation $f(x)=y$ has always at most one solution, ...

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What are your favorite instructional counterexamples on sequences?
1 votes

Directly referring to the phenomenon in the title: Consider $$x_n = \sum_{k=1}^n \frac{1}{k}.$$ Then for any $p$ and $n\to\infty$ $$|x_{n+p}-x_n| = \sum_{k=n+1}^{n+p}\frac1k \leq \frac{p}{n+1}\to 0.$$ ...

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