Triangle Similarity Update

As you may remember from my previous posts on this subject, I have been thinking a lot about the Common Core approach to secondary-school geometry, specifically the logical switcheroo that makes triangle congruence and similarity a consequence of assumptions about geometric transformations, rather than the other way around. To support this change, I have started… Continue reading Triangle Similarity Update

Rethinking Triangle Congruence and Similarity

As you may know, I have discussed transformational geometry and the Common Core State Standards for Math (CCSSM) several times on this blog. This summer, I have already been a presenter in two professional development workshops on transformational geometry, and will be involved in two more. This has pushed me to move forward on writing… Continue reading Rethinking Triangle Congruence and Similarity

Responses to my Common Core analysis

I have received excellent feedback about my analysis of the Common Core State Standards for high school math.E-mailed and spoken responses from my main hoped-for audience (high school math teachers) have almost without exception included a mention of having shared the paper with colleagues. For example:"I read your article about the Common Core on your… Continue reading Responses to my Common Core analysis

More Algebra Book Fan Mail

I have some good news for the users of the online version of Algebra: Themes, Tools, Concepts (ATTC, the textbook I co-authored with Anita Wah): all the ATTC PDFs are now searchable, and many of the files are smaller than they used to be. (See below for links.)Amanda Cangelosi, a Mathematics instructor at the University… Continue reading More Algebra Book Fan Mail

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

Transformational Geometry, cont’d.

As I mentioned in a recent post, I will be one of the presenters at the Bay Area Math Project's summer workshop on Transformational Geometry. As part of preparing for this, I went through my notes, and compiled a sort of syllabus of the relevant lessons from my Space course. Symmetry and transformations are the… Continue reading Transformational Geometry, cont’d.