Over the last few years I’ve made quite a few web applets. But they have been scattered all over the place. As a good end-of-semester project I decided to consolidate all of them and create an applets page. Enjoy.
Geogebra applet for families of discrete dynamical systems
As I mentioned recently, I taught the last two weeks of my colleague’s differential equations course. The topic was discrete dynamical systems. I posted links to a few Geogebra applets that I made, namely, applets for illustrating one-dimensional dynamical systems and an applet to generate cobweb plots for the logistic map. This is my third and…
Math Midway at the Da Vinci Science center
Yesterday we (my family and I) drove to Allentown, PA to go to the Da Vinci Science Center. We’d never been there before, and would have been interested in going anyway, but the reason for going now is that they are hosting the Math Midway exhibit (until January 6, 2010). More specifically, my son and…
Showing two expressions are equal: stop the madness
I know that most you who read my blog teach mathematics at either the high school or college level. I’d like to ask you a question (at the end of the post). It is about how our schools teach students to show that two mathematical quantities are equal. This has bothered me ever since I…
Twitter and Origami
Twitter is amazing. Two nights ago I watched the PBS documentary on origami, Between the Folds. Yesterday morning when I got to my office I made the following post on Twitter: In the next 12 hours I was flooded with suggestions, comments, and links. Here are some of the book titles and links that people sent…
Edublog award nomination
Wow, what an honor! My blog is now on the short list of Best Teacher Edublogs for 2009. I’d like to thank Brenda Landis for the nomination. Please head over to the site to vote for your favorite blogs! Voting ends Wednesday, December 16. By the way, I also encourage you to vote for Chris…
Mathematical holiday cookies at Starbucks
When I was in Starbucks the other day my eyes were drawn to the cookie display, for what did I see, but a row of cookies all decorated with ‘s! Upon closer inspection I discovered, to my disappointment, that it was not the Greek letter, but the red scarf of a polar bear. (As Homer…
Euler’s formula in a children’s book
As you may know, I wrote a book on Euler’s polyhedron formula. (Euler’s formula says that every polyhedron with V vertices, E edges, and F faces satisfies V-E+F=2.) I gave a talk recently during which I lamented that kids aren’t taught this beautiful theorem; after all, it relies only on counting, addition, and subtraction. After…
Cobweb plots for the logistic map: a Geogebra applet
A few days ago I posted Geogebra applets illustrating discrete dynamical systems. I was using these in a differential equations lecture that I gave. In the next lecture I showed the students how to draw cobweb plots for 1-dimensional discrete dynamical systems. A discrete dynamical system is a function in which the range is a…
An applet illustrating a continuous, nowhere differentiable function
Open any calculus book and you will find a discussion about how differentiability implies continuity, but continuity does not imply differentiability. The absolute value function is the standard example of a continuous function that is not differentiable (at ). The inquisitive student may ask: how bad can continuous, nondifferentiable functions get? Can we make a…
David Richeson: Division by Zero 