New on my Web site:→ Animated slides on the Lab Gear model for signed number arithmetic.Note that for each operation, the model is based on what students already know. For addition, you put down the first number, then the second number, and finally count. For subtraction, you put down the first number, take away the… Continue reading Animated Demonstrations
Tag: Geometry
Glide Reflections and Symmetry
Glide Reflections and Congruence
12th grade math options
I just posted Isometries of the Plane on my Web site. It is a transformational geometry unit aimed at high school teachers, and/or students in grades 11-12. It does go beyond the Common Core State Standards for Math (CCSSM), and thus might make sense as part of a precalculus course or a 12th grade elective.In… Continue reading 12th grade math options
Northern California December Events
I suspect that some readers of this blog do not subscribe to my newsletter, so I will use this post and the next to let you know about some news in my math education life. If you did get the November issue of the newsletter, you might read on anyway, as I will be going… Continue reading Northern California December Events
Programming and Math Education
Some responses on Twitter made me realize I was probably not clear in yesterday's post where I argued that computer programming is a kind of literacy. Some people say that students should be exposed to computer science because that's where the jobs will be in the future. There may be some validity to that, but… Continue reading Programming and Math Education
First Day of School
For most of you, school started recently, or will start soon. For me, this is the beginning of the third year of my retirement, and I'm starting to get used to the weirdness of my new life.It turns out that August is by far the most intense work month for me, because that's when I… Continue reading First Day of School
Triangle Congruence and Similarity tweaks
I just tweaked my documents on a transformational approach to triangle congruence and similarity, thanks to feedback from Bill McCallum.- Version 1 (more opinionated and footnoted)- Version 2 (co-authored with Lew Douglas, better section on similarity)The main change is to the SAS proof, which did not correspond to its illustration. If you downloaded earlier versions,… Continue reading Triangle Congruence and Similarity tweaks
Handwritten Pythagoras
Geometric Construction for Middle School
If you've been reading my blog for a while, you know that I'm a big fan of geometric construction. I have written about it here more than once, and my Web site includes quite a bit of curriculum involving construction. See the end of the post for additional links. I have many reasons for this… Continue reading Geometric Construction for Middle School
Henri's Math Education Blog 