This post is about a problem I learned about at Unsolved K-12, and was reminded of at Integer Sequences K-12. Both conferences were joint meetings of mathematicians and educators, organized by Gord Hamilton. Like several of my favorite problems from those conferences, this problem involved explorations on a lattice.Here is the problem:- You must get… Continue reading Ariadne’s String
Tag: Geometry
Perpendicular bisector theorem
Under the assumptions of the Common Core, the triangle congruence criteria (SSS, SAS, ASA) are no longer postulates. Instead they are to be derived from transformational geometry. There are many consequences to this state of affairs, and I have written about it on this blog: one, two, three. I have developed bits of curriculum, which… Continue reading Perpendicular bisector theorem
Geoboard Triangles
One way to discover or apply the formula for the area of a triangle is to explore area on the geoboard. The initial activities should be along the lines suggested in my Geometry Labs Lab 8.4. (Free download.)After that, one can zero in on triangles, by asking a question like: "Find triangles of area 15."… Continue reading Geoboard Triangles
Online Collaboration
In 2008, I gave a talk about teacher collaboration at the Asilomar meeting of the California Math Council. It was well attended, and well received, but more than a few attendees told me that they had no one to collaborate with. They were the only math teacher at their school, or the only one teaching… Continue reading Online Collaboration
NCTM wrap-up
I only attended a few sessions at NCTM-Boston, because I spent a fair amount of time promoting the Lab Gear. I already posted my report on Geoff Krall's strategies to improve the problems we find in standard textbooks. In this post, I'll go over some of the other worthwhile ideas I came across.- Scott Steketee… Continue reading NCTM wrap-up
Pattern Blocks
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 Geometry of the Parabola
Pie are square
Just in time for π day, I posted an animation that tries to show that the formula for the area of a circle is plausible. Check it out here. It is almost a proof that pie are square!--Henri
Pattern Blocks on Pi Day
I'll be offering a workshop for middle school and high school teachers on March 14 at the American Institute for Mathematics in San Jose. My topic is pattern blocks:<img alt="" height="76" src="data: Pattern blocks are ubiquitous in elementary schools, but they're not commonly seen in middle school or high school. Yet, they do offer plenty of… Continue reading Pattern Blocks on Pi Day
Summer Workshops, 2015
I'll be teaching four workshops this summer, in two new locations: Seattle, and Waltham, MA (which is a half-hour West of Boston.) If you've meant to attend my workshops in the past, but couldn't make it to San Francisco, New York, or DC, perhaps these venues are more convenient for you? There will be no… Continue reading Summer Workshops, 2015
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