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.
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Broken Ceiling Lights: Circular Area Without the Radius
Nicholas J. Gilbertson
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.
Using Public Records to Scaffold Joint Sense Making
Keith R. Leatham, Blake E. Peterson, Ben Freeburn, Sini W. Graff, Laura R. Van Zoest, Shari L. Stockero, and Nitchada Kamlue
Teachers can more productively use board work to scaffold joint sense making.
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.
Prove It! Graph Theory and Induction: The Next Big Thing
Jeffrey P. Smith
Eighth-grade students participated in a two-day lab exploring graph theory. In addition to learning about a completely new topic, they experienced a subtle introduction to proof by induction.
Let’s Be Flexible
Clayton Edwards and Rebecca Robichaux-Davis
Problems to Ponder
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.
Advancing Agency Through Conjecturing
Kristin Doherty
Support students in conjecturing in ways that can promote their agency in the learning process.
GPS: Teaching Shapes Inclusively
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.
Making Sense of Algebraic Expressions in Context
Isabel White, Michael Foster, and Joanne Lobato
Explore three challenges that students faced and how they made progress.
