The author shares geometry that inspires him.

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## The Beauty of Regular Hexagons

### Arsalan Wares

## Broken Ceiling Lights: Circular Area Without the Radius

### Nicholas J. Gilbertson

A customer walks in to a lighting store with a broken ceiling light, and the solution to finding a replacement glass illuminates an alternative approach to finding the circumference and area of a circle without knowing the circle’s center, radius, or diameter.

## Problems to Ponder

### Chris Harrow and Justin Johns

Problems to Ponder provides 28 varying, classroom-ready mathematics problems that collectively span PK–12, arranged in the order of the grade level. Answers to the problems are available online. Individuals are encouraged to submit a problem or a collection of problems directly to mtlt@nctm.org. If published, the authors of problems will be acknowledged.

## Adapt It! Adapting Stories and Technology for Engagement in Geometry

### Karen L. Terrell, Dennis J. DeBay, and Valerie J. Spencer

A task to develop and provide access to mathematics for all.

## Construct It! Progressively Precise: Three Levels of Geometric Constructions

### Carmen Petrick Smith

This article shares an activity scaffolding the construction of the circumcenter of a triangle, culminating with a Triangle-Ball Championship game.

## Construct It! Triangle Puzzle Challenges

### Enrique Ortiz

This article presents an original puzzle that supports students’ development of visual thinking and geometry ideas based on the Van Hiele levels of geometric thought.

## GPS: Building Popcorn Boxes

### Robert A. Powers and Michelle T. Chamberlin

Growing Problem Solvers provides four original, related, classroom-ready mathematical tasks, one for each grade band. Together, these tasks illustrate the trajectory of learners’ growth as problem solvers across their years of school mathematics.

## Imagine It! Choose Your Own Pattern Block Adventure

### Anita A. Wager, Brittany Caldwell, and Jamie Vescio

When given the opportunity to play with mathematical materials and ideas, children demonstrate their mathematical understanding in innovative ways.

## Model It! Building and Sustaining Cultural Traditions with Ethnomodeling

### Siddhi Desai and Farshid Safi

This geometric transformation-focused ethnomodeling respects individual and collective community experiences and moves toward educational experiences that acknowledge and celebrate the multidimensional aspects related to identity.

## The Do Nothing Machine

### Keith Dreiling

The Trammel of Archimedes traces an ellipse as the machine’s lever is rotated. Specific measurements of the machine are used to compare the machine’s actions on GeoGebra with the graph of the ellipse and an ellipse formed by the string method.