If you’re a regular reader of this blog, or visitor to my website, you probably know of my long-standing interest in geometric puzzles. Among those, tangrams are probably the most well-known and widely available. Thus I included them in Geometry Labs (free download) where they are the subject of Section 2, and Lab 10.6. In this… Continue reading Convex Tangram Polygons

# Blog

## An Assessment Conundrum

On Twitter, Nick Corley writes: Students were SUPPOSED to use the distance formula, but look at the response in the pic. How do you grade????? This is a great discussion starter! Here are my thoughts. Assessment Should the student be penalized for finding the correct answer, using a correct method? That would be particularly egregious… Continue reading An Assessment Conundrum

## Teachers’ Mathematics

I recently came across an interesting and humorous lesson, intended to generate discussion and reflection about the properties of our number system. It is based on the idea of a fictional cashier who knows absolutely nothing about numbers. The worksheets (Tarzan 1 | Tarzan 2) were created by mathematician Robin Pemantle for use in a… Continue reading Teachers’ Mathematics

## Math as Literacy

This may be the only country where there is an ongoing campaign against high school math — in the media, in the overall culture, and even within the profession. I have written a number of posts in response to that state of siege, and I link to them below. Here is the ninth installment in… Continue reading Math as Literacy

## Rate of Change

I often promote the idea that if a concept is important, we should teach it more than once, and preferably in more than one way. Rate of change is one such concept. It can be approached in various ways from middle school to calculus. Is there anything to add to the oft-repeated “rise over run”… Continue reading Rate of Change

## PCMI

In 2006, I attended the Park City Mathematics Institute. I shared some of the work I did there on my website. Here is some information about this summer’s program, from the amazing Peg Cagle. -- Henri —————————————————————————————————— An immersive, three-week residential program, the Park City Mathematics Institute / Teacher Leadership Program provides participating secondary math… Continue reading PCMI

## Seen Elsewhere

Today, I share some materials not from my website — though not unrelated! Robert Wirtz As a young elementary school teacher and math specialist in the 1970’s I came across Robert Wirtz’s materials, and was inspired by them. Here is an example, the one I call “Wirtz’s flags": The idea is to draw vertical lines,… Continue reading Seen Elsewhere

## Course Evaluations

I’ve written at length about assessment — the assessment of students by teachers. Today, I turn around and focus on how to maximize the benefits of student feedback in course evaluations. Early in my high school teaching career, I was given a form that my students were supposed to fill out. It had a long… Continue reading Course Evaluations

## Classroom Basics

Last January, I addressed a blog post to a “young teacher”. Actually, it applied to beginners — whether young or not so young. The post was largely about big-picture thoughts on becoming a math teacher. It generated a thoughtful and heartfelt response from another veteran educator. If you’re a beginner, I encourage you to check… Continue reading Classroom Basics

## For Algebra

The Atlantic published an excerpt from Temple Grandin’s latest book (Visual Thinking). They titled it “Against Algebra”, which puts it in a tradition of anti-algebra pieces in various magazines and radio programs (!). Alas, anti-algebra ideas are also present among some math educators. I have written about this repeatedly: Technology in Math Education (2022) My… Continue reading For Algebra