Pick's formula is a way to find the area of a geoboard polygon by counting interior pegs and boundary pegs. Students can discover the formula by doing some experimenting under teacher guidance (see Geometry Labs 8.6 or Algebra: Themes, Tools, Concepts 4.12.) I have used this in the classroom for decades, because it is such… Continue reading Proving Pick’s Formula
Tag: Manipulatives
Another "K-12 Unsolved" Problem
In a recent post, I mentioned a problem posed in 1917, which remains unsolved and which lends itself to use in K-12 education:Consider an n by n lattice. Is it always possible to choose 2n points in it so that no three points are in a line? Today, I present a related unsolved problem I… Continue reading Another "K-12 Unsolved" Problem
Algebra: Themes, Tools, Concepts and the Common Core
Way back in the early 90's, I co-authored the textbook Algebra: Themes, Tools, Concepts (ATTC) with Anita Wah. It failed to become a best-seller, in part because while the lessons work well with students, the book is not very easy for teachers to manage. Still it's a good book. We have continued to use different… Continue reading Algebra: Themes, Tools, Concepts and the Common Core
Summer Workshops
I'll be teaching four workshops in June, at the Urban School of San Francisco's Center for Innovative Teaching. I just posted the info here. Some changes from past years:I've broken up my Geometry workshop, which used to be three or four days, into two chunks, two days each. The first (Hands-On Geometry) will be based… Continue reading Summer Workshops
No Three on a Line
In a recent post, I mentioned K-12 Unsolved, the project I'm involved in that aims to publicize 13 unsolved math problems, in the hope that an appropriate version of each problem will find its way into K-12 classrooms. One problem we looked at was posed by Henry Dudeney in 1917. Here is the problem: Consider… Continue reading No Three on a Line
Geoboards and Dot Paper
If you are familiar with my curricular creations, you know that I often use the geoboard as a microworld to introduce interesting problems and important concepts. This is in line with my call for a tool-rich pedagogy. (A geoboard is a square lattice pegboard on which students use rubber bands to create and investigate geometric… Continue reading Geoboards and Dot Paper
"Enrichment"
During my first ten years as a teacher, I worked in elementary schools. In addition to team teaching my own class (grade 3, then 4, then 5) I was a math specialist for grades K-5. The basic idea was that there was "normal" math (a lot of arithmetic, textbook-based), and there was "enrichment" math. I… Continue reading "Enrichment"
Straightedge and Compass
Back when I was a high school student, I had mixed feelings about compass and straightedge constructions. On the one hand, I liked the geometric challenge, on the other hand, I hated the physical challenge of working with an actual compass. Maybe 20 years later, I had exactly the same experience as a high school… Continue reading Straightedge and Compass
Upcoming workshop and presentations
I'll be offering a workshop at East Bay Charter Connect's Third Annual Charter School Symposium on Friday, October 11, in Oakland, CA. My theme is "Connecting the Dots (math on the geoboard and dot paper)". This will include selected topics in algebra and geometry: area, distance, the Pythagorean theorem, simplifying radicals, dilation, slope, and more!… Continue reading Upcoming workshop and presentations
Math and Art
Many years ago, I team-taught a class called "Math and Art" with my then-colleague Stephen Thomas, who was an art teacher at The Urban School. Like most such endeavors at any school, the class was short-lived — I believe we offered it twice. However it was not in vain: some of that curriculum found its… Continue reading Math and Art
