I've really enjoyed solving the puzzles in Euclidea, a brilliantly designed app for iOS and Android. The basic format is "given this, construct that". You start with just two tools: a straightedge and a slack compass (i.e. a compass that does not remember the radius it was last set to). As you find useful and… Continue reading Stumped by Euclidea

# Tag: Manipulatives

## More on Geometric Construction

(To search from previous posts on this topic, use the Search box on the right.) I suspect that by far the most common introduction to geometric construction in US classrooms is a presentation by the teacher (or textbook) on various compass and straightedge construction techniques. "This is how you construct a perpendicular bisector. This is… Continue reading More on Geometric Construction

## Geoboard Problems for Teachers

At the San Francisco Math Teachers' Circle yesterday (March 4, 2017), we explored four "teacher-level" geoboard problems (All can be adapted for classroom use.) Here is a brief report, including some spoilers, I'm afraid. Pick's Formula It turns out that the area of a geoboard polygon can be figured out by counting the lattice points… Continue reading Geoboard Problems for Teachers

## Geometry Boot Camp!

I will offer two workshops this summer (2017), at the Head-Royce School in Oakland, CA. Sign up for either or both! June 26-27: Hands-On Geometry (grades 6-10) June 28-30: Transformational Geometry (grades 8-11) If the times or locations don't work for you, I can offer a workshop for your school or district. Contact me directly.… Continue reading Geometry Boot Camp!

## Algebra Manipulatives

A middle school teacher writes: Just a little note and question about Lab Gear. I have been having so much fun with my students using Lab Gear again this year. The 3D-ness of it totally blows the other (cheaper) algebra tiles that I used last year out of the water! I have heard this often… Continue reading Algebra Manipulatives

## More Notes from NCTM Phoenix

See Part 1 of my notes from Phoenix: A Brief History of Math Education (NCTM President Matt Larson's presentation.)Here is Part 2.Growth Mindset: telling is not teachingIn his short session, Dylan Kane pointed out that talking about growth mindset may be helpful to students "in the middle". But there are students in our classes who… Continue reading More Notes from NCTM Phoenix

## Reading Algebra

Symbol sense is an essential part of mathematical literacy. It is the understanding that undergirds effective symbol manipulation, and perhaps more basically the ability to interpret and create algebraic expressions. Symbol sense, like number sense and operation sense, is not learned so much through listening to a teacher. Rather, it grows as one gets practice… Continue reading Reading Algebra

## Big Dodecagon

A classic activity is to cover a 1-inch-side dodecagon with pattern blocks. This provides a great context to discuss symmetry (see Geometry Labs 5.6.) Here is one way to do it:See many others, found by Simon Gregg's students.In the past few days, I've had fun making a double-size, quadruple-area dodecagon: You too, and… Continue reading Big Dodecagon

## Eclectic

In between June 27 and August 4, 2016, I presented seven to ten workshops (depending on how you count) ranging from a couple of hours to four days. I share most of the handouts, resources, and slides on my Summer Workshops site. (See below my signature for more details on what's there.)The site will remain… Continue reading Eclectic

## Fractions

I have a new Fractions mini-home page, with links to three pages on my site. In this post, I'll use it as an excuse to discuss some general ideas about teaching.Visual RepresentationsIn my Fraction Arithmetic page, I present a visual strategy for figuring out how to add, subtract, and multiply fractions. (There is also a… Continue reading Fractions