I am busy preparing for my summer workshops, so I'm blogging less and adding more stuff to my Web site.Here's a list of recent additions:- A new Geometric Construction page, including a whole unit with a teachers' guide, plus a GeoGebra page with tools limited to straightedge and compass construction. Also an applet / file… Continue reading New stuff on my Web site
Tag: Geometry
Astronomy and Geometric Construction
In the days preceding a recent lunar eclipse, my daughter saw an illustration that seemed to show that the Moon's diameter was just about equal to the width of the penumbra. She conjectured that if that were true, it may be because of the fact that the apparent diameter of the Moon (as seen from… Continue reading Astronomy and Geometric Construction
Pythagorean animation
Check out a GeoGebra animation I just posted: the Pythagorean theorem.It bears much discussion, as students are not likely to spontaneously make out its significance. One way to present it to a class is to first go through the whole thing on a projector, then go back through it slowly, discussing the meaning of each… Continue reading Pythagorean animation
Sum of the angles
New animation: Sum of the Angles in a Triangle. This is in the genre of "proofs without words", but of course its pedagogical power comes from students and teacher actually using words to discuss what happens.--Henri
The Human Unit Circle
In 2010, I wrote a series of posts on kinesthetic activities for secondary school math. I combined all of them into one page on my Web site, which I introduced thus:One way to break up the routine in math class is to have the students get up and experience some of the concepts in their… Continue reading The Human Unit Circle
area of a parallelogram
I posted a GeoGebra animation that suggests the formula for the area of a parallelogram defined by two vectors: <img alt="" height="200" src="data: <img alt="" height="200" src="data:--Henri
Middle School
I have taught grades K-5, high school, future teachers, and working teachers, but I have never taught middle school, except for a couple of summer jobs some years ago. Nevertheless, my curriculum materials are widely used at that level, and maybe half the teachers I have worked with are middle school teachers.I just started a… Continue reading Middle School
The Geometry of the Parabola
Parabolas are a central topic in high school algebra classes, but, perhaps because of the rigid separation between algebra and geometry classes in the US secondary curriculum, we do not usually treat them as geometric objects. While most teachers are aware of some of the parabola's geometric properties, few of us are familiar with the… Continue reading The Geometry of the Parabola
Saturday workshop
I will present a workshop at the the Math Teachers' Circle in Palo Alto (at the American Institute of Mathematics.) The topic is area on a lattice, which we will explore on geoboards and dot paper. We will discuss "curricular" classroom applications (the Pythagorean theorem, simplifying radicals) as well as Pick's theorem and its proof,… Continue reading Saturday workshop
The Common Core
Now that I'm a freelance math education consultant and curriculum developer, I need to pay attention to the Common Core State Standards as they affect everything I do in my professional life. Merely listening to talks about the standards, and reading angry posts about them did not provide a lot of information. On the other… Continue reading The Common Core
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