**2-6 August 2021**: With Rachel Chou, I will present an online workshop — **No Limits!** for teachers of Algebra 2, Trigonometry, and Precalculus. Hosted by Menlo School. **Register**.

**19-23 July 2021**: ~~I will present an online workshop on “Symmetry: A Unifying Thread Across Grades and Cultures”.~~ The Symmetry workshop has been canceled.

**June 2021**: My arithmetic games (**Signed Numbers**, **Complex Numbers** — my design, programmed by Parisa Safa) are temporarily unavailable. The Snap! website is addressing a security flaw.

**7 April 2021**: I sent out **my e-newsletter**, which included links to my recent blog posts (**Seeing is Believing?**, and **Fraction Rectangles**, and to the new **Pentomino Puzzle Books** page on my website. I also used the newsletter to promote my **summer workshop**.

**March 2021: **My arithmetic games (**Signed Numbers**, **Complex Numbers**) now load fast from the Snap! website. (My design, programmed by Parisa Safa.)

**11-12 Mar 2021** (4pm to 4pm Pacific Time): I participated in the Julia Robinson Math Festival’s **Math Buffet**, an international 24-hour online event for kids (and adults).

**23 Feb 2021**: I sent out **my e-newsletter**, which included links to my recent **Tiling** and **Transformational Geometry** blog posts, and to the new **Symmetry** home page on my website.

**9 Feb 2021**: Math Teachers’ Circle: **Tangrams** and **Pentominoes** are **geometric puzzles** which are fun and interesting for all ages. Can students use these manipulatives in an age of remote instruction? Yes! In this workshop, I shared virtual tools I created to make that possible. I proposed problems suitable for ages 9-99, and participants worked as a team to generate dozens of solutions. The activities touched on symmetry, area, congruence, and similarity.

**6 Dec 2020**: I presented “**Symmetry**: a unifying thread across grades and cultures” at the California Math Council-North virtual conference. We explored line and rotational symmetry with activities on free online platforms. We analyzed examples from all over the world. Bonus: links to online symmetry projects, as well as hands-on activities using mirrors, pattern blocks, tangrams, pentominoes, templates, and special papers for when you’re back in the classroom. (See my **Talks** page for info.)

**2 Dec 2020**: I restored the graphics in **Math in the Long Period**.

**10 Nov 2020, 4:30-6:00pm PST: **AC3ME and SFMTA (two Bay Area NCTM affiliates) hosted my workshop about some of my website’s

**free virtual manipulatives**(Geoboard, Grid Paper, Lab Gear, Tiling, Pentominoes.) I showed how to use them, and suggested a problem for each one so that participants can practice then and there.

**29 Sep 2020: **I sent out **my e-newsletter**, which was largely focused on **virtual manipulatives**. I announced two upcoming online workshops: Nov 10, on virtual manipulatives (grades 6-12), and Dec 6 at the California Math Council North annual meeting) on **symmetry**.

**17 June 2020**: I sent out **my e-newsletter.** Topics included: “There is no one way”, a GeoGebra animations tutorial, sum and difference of cubes, Lab Gear graphics, symmetry, and my wallpapers catalog. Also: an announcement of my** online summer / fall workshop** — Hands-On Geometry.

**15 June 2020**: My July Hands-On Geometry summer workshop will happen online, assuming sufficient enrollment. The August iteration has been postponed to four Saturdays in September and October. I will be updating the **summer / fall workshop** page on my website as I get more information.

**28 May 2020:** I restored a post (**Symmetry in Spain**). Math-relevant photos, and links to photos, from a vacation in 2013.

**10 February 2020:** I sent out **my e-newsletter.** Topics included guided inquiry, conic sections, a polyomino puzzle, a grid approach to fractions, graphing ax+by=c, and number pyramids. Also: an announcement of my **summer workshop** — Hands-On Geometry on both coasts. Alas, there was a wrong date for the latter, and a couple of broken links. It’s all fixed online!

**4 February 2020**: Infinity is a mind-bending topic that everyone finds interesting. I shared infinity paradoxes, puzzles, problems, and proofs from a **high school course** I developed at the Berkeley Math Teachers’ Circle.

**7 December 2019**: At the Asilomar conference, Kim Seashore and I presented **Lessons from Lew**. (Kinesthetic angles, Golden Ratio, Symmetric Polygons.) Later, I presented **Connect the Dots, **an extravaganza of **geoboard / dot paper activities** for ages 9 to 99: curricular challenges, interesting puzzles, and some unsolved problems.

**26 November 2019**: I restored the graphics in my post **Completing the Square**.

**30 October**: I sent out **my e-newsletter**. The main topics were test retakes and a response to Freakonomics Radio episode about math education. I also highlighted recent contributions to my blog and website by Rachel Chou.

**5 October 2019**: Along with Kim Seashore, I was a presenter at **Lessons from Lew**, a free professional development session. We shared Lew Douglas’s lessons on angles, the golden ratio, symmetric polygons, and more. Links to an expanded version of the handouts, here.

**18 September 2019**: I added a **link** to Chris Bolognese’s Desmos Activity Builder version of **Add Till It’s Plaid**, a lesson plan on solving systems of linear equations.

**12 September 2019:** I restored the graphics in my post **Add Till It’s Plaid**, wherein I share a great lesson on solving systems of linear equations.

**10 September 2019**: I restored the graphics in my post **Making a Vector in Desmos**.

**23 August 2019**: I sent out **my e-newsletter**.
The main topics were: “Taking Notes vs. Doing Math”; a review of a book
that was a big influence on my teaching; the place of puzzles in math
education. Plus a lot more. **Subscribe**!

**17 August 2019**: An entire post (about Doctor Dimension, the flat scientist) was missing. **I restored it**.

**5 July 2019:** I fixed more broken links, this time in a series of posts in which I challenge the dogmatic stance of teachers who are overly stingy about offering hints to students who are stuck: **About Hints**, **About Hints, the sequel**, and **Hints! The topic that will not die**.

**1 July 2019:** I fixed broken links to **I’ve Got a Problem**!, the first of two posts about a time where I was in the student’s shoes, and I learned a lot from it.

**18 June 2019: **I restored the figure in G**eometric Series****, **a blog post about a geometric way to visualize the case where the common ratio is less than 1.

**18 April 2019: **I
restored the graphics and repaired the links in my 2011 notes from a
meeting of Escape from the Textbook! a grassroots math teacher group
that met for a few years in the Bay Area.

(**Part 1**: tools, backward design | **Part 2**: Miras | **Part 3**: habits of mind)

**12 April 2019**: I restored the graphics in the **Partitions** post.

**3 April 2019**: I restored the graphics in the **Egyptian Fractions** post.

**15 March 2019**: I sent my **e-newsletter**
out. The main topics were story tables, an argument against the
shrinking of geometry, a book review, geoboards + related topics, and
the announcement of my summer workshops. **Subscribe**!

**6 March 2019**: I fixed a broken link to **Puzzles for the Classroom** in the post **Puzzle Creation**.

**20 February 2019**: I restored a missing equation from **Pruning the Curriculum**, a 2015 blog post where I suggested teaching fewer topics in more ways. I also fixed a link to the related **Mapping Out a Course**.

**5 February 2019, 5pm**: **Geoboard Puzzles and Problems**. I led the East Bay Math Teachers’ Circle at Berkeley High. The geoboard is a great learning environment, but in this session we used it as an arena for puzzles and problems, some of them unsolved, involving diagonals, triangles, non-triangles, and zigzags! You can download **the handout**.

**25 January 2019**: I sent my **e-newsletter** out. The main topics were learning tools, and the announcement of my summer workshops. **Subscribe**!

**14 January 2019**: I restored five posts about the geoboard: **Geoboard Triangles**, **No Three on a Line**, **Heilbronn’s Triangle**, **Ariadne’s String**, and **Geoboard Problems for Teachers.**

**9 January 2019:** I will offer a grades 6-9 version of my workshop on **Visual Algebra** twice this summer: June 25-27 at Synapse School in Silicon Valley, and again August 7-9 at Atrium School near Boston. **More information**.

**9 January 2019**: I restored the graphics in two posts: **“A New Algebra”** where I bragged about Robert Davis’s praise for my approach; and **Geoboards and Dot Paper**, where I introduced subsequent posts on using these tools as a microworld for problem solving, and bragged about having invented the “tilted squares” intro to the Pythagorean theorem decades ago.

**8 January 2019**: I restored the post** ****Themed Courses?****,** where I discuss the question of whether courses with a theme are preferable to “hodgepodge” courses, whose topics range widely.

**8 January 2019**: I restored the graphics in two posts: **Inscribing Geoboard Squares in Polyominoes**, a fun puzzle; and my 2014 **Asilomar Report**, which included interesting material about warmups.

**28 December 2018**: I restored the post **Tiling, aka Tessellation**, where I summarized some sessions at Twitter Math Camp, and linked to the various **tiling items** on my Web site.

**28 December 2018**: I restored the illustration in the **“Enrichment”** post.

**24 December 2018: **I restored the posts **Geometric Construction, Continued **and **Programming and Math Education. **

**24 December 2018: **I restored the diagram in the** Curriculum Model **post. The figure was the subject of the post! Also: I restored the graphics in the **Make These Designs** post.

**22 December 2018: **I restored the **Math for Equity **post, where I reviewed an excellent book about “Railside” school, where teachers developed tremendously effective approaches to teaching untracked classes in a “wrong side of the tracks” school. Their work was studied by math education researchers at both Stanford and Berkeley.

**22 December 2018: **I restored the “themes, tools, concepts” map in the **Proportional Relationships **post. That diagram was the main point of the post, so I feel bad that a few dozen visitors to the page didn’t get to see it.

**22 December 2018**: I restored the **Time and Tide** post, where I link to and discuss my three (!) presentations at Asilomar (2016), and propose some strategies to slow things down in classroom discussion.

**21 December 2018**: I restored the graphics in the **Algebra Manipulatives **post, where I compare the Lab Gear with other models, and reply to a correspondent. Also the illustration in **Straightedge and Compass**.

**17 December 2018**: I restored the **Geoboard Problems for Teachers** post. Surprisingly to me, this was one of my most visited post ever.

**15 December 2018**: I restored my **Polyarcs** post, which had not survived the move to WordPress. Interesting discussion in the comments!

**14 December 2018**: I found the graphics from my **Stumped by Euclidea** blog post on the Internet Archive’s Wayback Machine! It was a bit of work to put them back into the post, but not as much work as recreating them! I’ll continue to work my way back through the posts to restore content lost in the move from Blogger.

**1 December 2018**: I attended the California Math Council Northern Section meeting in Asilomar. My presentation was about *Reaching the Full Range* of students in a heterogeneous class (i.e. any class). I put lots of links about this on my **Talks** page.

**27 November 2018:** I moved my blog into WordPress (here.) I thought the move had happened smoothly, but some graphics, and some entire posts, failed to materialize. Also, many links are broken. If you come across these problems, please **notify me**, indicating which post had the issue. Thanks!