# Posts tagged as: do the math

## Place Value: How to Assess Students’ Understanding

by Math Solutions Professional Learning Team, February 20th, 2019

If you’re familiar with Cooks Illustrated magazine, you know that they use their test kitchen to tinker with recipes and improve on them. In each issue, they report on all of the attempts they make and then finally present a recipe they recommend. In a way, I feel as if my search for a way to assess…

## Why I Like Using Open Number Lines (Though I Don’t Like the Name)

by Math Solutions Professional Learning Team, December 13th, 2016

This post is about subtraction, which is typically difficult for students to learn and for teachers to teach. Think about 503 – 398, for example. To estimate the answer, I can change the problem to 500 – 400 (rounding 503 to 500 and 398 to 400). That gives me an estimate of 100, which I know is close. But how can I know if the actual answer to 503 – 398 is greater or less than 100? I raised this question with third graders.