DecimalsGeneral InterestMultiplicationNumber and OperationsNumerical ReasoningReal-World ProblemsVideosWord Problems

When You Multiply by 10, Just Add a Zero? Horrors!?!

Have you ever asked students to solve 12.6 x 10, and they respond that the answer is 12.60? I have, many times. Students who do this apply a pattern that works when they multiply whole numbers by 10—they tack on a zero to the end of the number they’re multiplying. But then they apply the same pattern when working with decimals. What can we do?
October 1, 2018
General InterestProblem SolvingVideos

When Should and Shouldn’t We Give Answers?

Over a year ago, I blogged about The 1–10 Card Investigation. I didn't provide a solution to the problem and no one who commented asked for one. But a newly posted comment requested the solution. That pushed me into a conversation with myself about how I should respond, and about giving answers in general.
February 5, 2017
AlgebraGeneral InterestProblem SolvingVideos

An Oldie Revisited: The Border Problem

Here's one of my favorite oldies. (No, not the photo—the border problem.) I was so pleased to see this math investigation included in Jo Boaler’s latest paper. This blog post presents a detailed lesson plan for using the border problem with students and also includes a five-minute video clip to give you a sense of how the instruction went with one class.
April 19, 2016
General InterestProblem SolvingVideos

The 1–10 Card Investigation

The 1-10 Card Investigation has a big payoff with students. It engages their interest, involves them with making sense of a problem and persevering to solve it, and gives them experience with evaluating their progress and changing course as necessary. Plus it has a playful aspect that too often is lost in math class.
June 29, 2015
General InterestVideosWord Problems

Word Problems

Word problems have long been difficult and frustrating for students to solve and for teachers to teach. A colleague recently forwarded an email from a woman looking for resources to help her fourth-grade granddaughter with word problems. I thought for several days about how to offer positive support to both the grandmother and her granddaughter.
March 10, 2015