I blogged a few years ago about starting geometry with developing definitions. I've made some changes since then, and I have additional ideas for next year that I want to remember. I've found it more useful to start the school year introducing geometry as art, and developing a need for definitions as students struggle to … Continue reading Definitions in Geometry update

# Geometry

# Going full circle completing the square

I usually use the last six week of the school year in geometry to teach circles: Arc lengths, chords, secants, tangents, etc. Which I have outlined in the Geometry Planning Guide The following school year students begin Algebra 2 and promptly forget these properties of circles. They also start the new school year frustrated and … Continue reading Going full circle completing the square

# Rolling Cups: Modeling in Geometry

The Rolling Cups task from the Shell Center is a perfect geometry modeling project. I use some form of this task every year for the last three days of the first semester as a final project. This task incorporates constructions, similarity, functions and modeling while pre-assessing students readiness for next semester's content: solids and circles. … Continue reading Rolling Cups: Modeling in Geometry

# A low-tech unit studying quadrilaterals

In an effort to be better at sharing quality basic stuff that works, here's how I teach quadrilaterals: I am hesitant to share the files that I use because I've borrowed them from all over the interwebs and at this point I don't even know where to give credit, but here they are! [10/11/16 update: Most … Continue reading A low-tech unit studying quadrilaterals

# Analyzing Triangle Congruence with AngLegs

I've tried to explain why AngLegs are a must have for high school geometry and should not only be considered a tool for younger students. Here is an example of how I find them indispensable in teaching triangle congruence. This lesson is adapted from MARS: Evaluating Conditions for Congruency. "Ok class, you are sitting in pairs and at … Continue reading Analyzing Triangle Congruence with AngLegs

# Painless Proofs!

"I felt guilty for not including proofs in enough detail and I decided that this year I was going to teach it well. Here is what I did:"

# Constructions was MUCH better this year!

Last year I wrote a post about how I wanted to improve my teaching of geometric constructions this year. This year, I re-read it and used it to help plan this unit better. I never provided the students with steps to make constructions! It was tempting, but I resisted the urge, and they did great! Here … Continue reading Constructions was MUCH better this year!