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
Blog
Ripples
Math curriculum ideas expand outward from their originators, like ripples in a pond. In pre-Internet days, it was great to see teachers using photocopies of photocopies of photocopies of worksheets I created, such as "Make These Designs." Nowadays, of course, people can always download and print a fresh copy. One day at an NCTM meeting,… Continue reading Ripples
More Algebra Book Fan Mail
I have some good news for the users of the online version of Algebra: Themes, Tools, Concepts (ATTC, the textbook I co-authored with Anita Wah): all the ATTC PDFs are now searchable, and many of the files are smaller than they used to be. (See below for links.)Amanda Cangelosi, a Mathematics instructor at the University… Continue reading More Algebra Book Fan Mail
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
Egyptian Fractions
I had a great time at the Julia Robinson Math Festival the weekend before last. Hundreds of kids attended, most of them girls, it seemed to me. The setup: many, many tables; at each table, one or two adult guides, and a math problem that combines access and depth. Students choose a table, and work… Continue reading Egyptian Fractions
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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