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.

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### Chris Harrow and Justin Gregory 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.

### Krystal Jones Carter

A well-crafted classroom engineering challenge can effectively answer compelling questions about social and global responsibility.

### Samuel Otten, Tiffany J. LaCroix, Faustina Baah, and Rebekah Hanak

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.

### Travis Lemon and Scott Hendrickson

A robust framework can support teachers and their students’ learning.

### Laura Bofferding and Yi Zhu

Different types of tangram puzzles can encourage students to make sense of problems and engage in the computational thinking practice of debugging.

### Chris Harrow, Justin Johns, and Hassan Lakiss

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.

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

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.

### Arsalan Wares and David Custer

This pattern-related problem, appropriate for high school students, involves spatial visualization, promotes geometric and algebraic thinking, and relies on a no-cost computer software program.