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.

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### 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?

### 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.

### Manouchehri Azita, Ozturk Ayse and Sanjari Azin

In this article we illustrate how one teacher used PhET cannonball simulation as an instructional tool to improve students' algebraic reasoning in a fifth grade classroom. Three instructional phases effective to implementation of simulation included: Free play, Structured inquiry and, Synthesizing ideas.

### Aline Abassian and Farshid Safi

This article dives into the importance of engaging students in investigating the mathematics of businesses that pressure their members to recruit new members as a basis for success, also referred to as multi-level marketing (MLM). The mathematics behind these businesses are discussed, and a sample student task is given.

### Trena L. Wilkerson

How has NCTM leadership shaped the evolution of teaching and learning mathematics? What are your expectations for NCTM leadership?

### Jon Orr and Kyle Pearce

Wondering how to create a classroom culture where students don't want to stop exploring mathematics when the bell rings? We were too and that's why we teammed up to uncover how we can Make Math Moments That Matter for every student in the math classroom with a weekly podcast.

### Jennifer A. Czocher, Diana L. Moss and Luz A. Maldonado

Conventional word problems can't help students build mathematical modeling skills. on their own. But they can be leveraged! We examined how middle and high school students made sense of word problems and offer strategies to question and extend word problems to promote mathematical reasoning.