In my previous post, I presented a number line model for adding fractions. Now, I'd like to offer an updated Web Sketchpad fraction model below (and here) with two new pieces of functionality:

You can subtract as well as add fractions.

You can divide the number line into equal parts and choose the … Continue Reading ››

On the NCTM discussion site myNCTM, there's currently an extended discussion about "Division and multiplication of fractions." As the discussion has continued, I've grown concerned with what I see as a fundamental problem with the way we often introduce multiplication as repeated addition: "Multiplying 4 by 5 means we're combining five groups of four items. … Continue Reading ››

We created the Web Sketchpad game below (and here) as part of our Dynamic Number project. It challenges elementary-age students to uncover the value of a secret number by collecting and analyzing clues that narrow its range of possible values. The game familiarizes students with inequality signs, introduces the use of x to represent … Continue Reading ››