Teachers have the opportunity to make mathematics relevant. We leveraged the popularity of *Star Wars* to engage students in exploring and connecting two dimensions and three dimensions to careers in toy design.

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## Using Mathematics to Design a Droid

### George J. Roy, Matthew Cunningham, and Kenneth Rafanan

## The Hidden Beauty of Complex Numbers

### Juan Carlos Ponce Campuzano

## Golden Circles

### Paula Beardell Krieg

An artist uses graphic tools and circles to illuminate the illusive concept of the golden ratio.

## The Mathematical Wonders of 3D Printing

### Gavin Cunningham and Siddhi Desai

We share how engaging in the mathematical process of 3D printing captured and elevated our interest in discovering the wonder, joy, and beauty of mathematics in the world around us.

## Understanding the Real World: Sweaty Jo

### Jill P. Brown

Mathematics can be used to show why babies should never be left alone in a hot car.

## Integrating Machine Learning in Secondary Geometry

### Joshua Jones

Despite the importance of artificial intelligence in our daily lives, it has yet to be integratedinto K–12 classrooms in a meaningful way. Explore a lesson in which geometry students useEuclidean distance to implement a functional machine learning algorithm in Google Sheets™.

## Conditional Reasoning Online with Mastermind

### Sean P. Yee, George J. Roy, and LuAnn Graul

As mathematical patterns become more complex, students' conditional reasoning skills need to be nurtured so that students continue to critique, construct, and persevere in making sense of these complexities. This article describes a mathematical task designed around the online version of the game Mastermind to safely foster conditional reasoning.

## Escape Room Math: Luna's Lines

### Micah S. Stohlmann

An escape room can be a great way for students to apply and practice mathematics they have learned. This article describes the development and implementation of a mathematical escape room with important principles to incorporate in escape rooms to help students persevere in problem solving.

## GPS: Equivalent Expressions

### Matt Enlow and S. Asli Özgün-Koca

Equality is one of the main concepts in K–12 mathematics. Students should develop the understanding that equality is a relationship between two mathematical expressions. In this month's GPS, we share tasks asking students one main question: how do they know whether or not two mathematical expressions are equivalent?

## Investigating Using Lesson Study

### Scott Corwin, Michelle Cascio, Katherine Emerson, Laura Henn, and Catherine Lewis

Our middle school mathematics department used lesson study to investigate how to introduce fractions division to our sixth-grade students. We highlight our learnings during the Study and Plan phases, describe our observations during the lesson, and provide tips for educators interested in using lesson study to study their own content.