The Math Education Blog
Given a strip of paper, how might you divide it into fourths without using a ruler? Undoubtedly, you’d fold the strip in half and then in half again to locate the quarter marks. Now suppose that your goal is to divide a strip into sixths. You might start by folding the strip into thirds and...
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....
In my recent posts, I’ve introduced interactive models for comparing fractions and multiplying fractions. To continue the fraction theme, below (and here) is a Web Sketchpad model in which the need for equivalent fractions arises naturally through the rules of a game. The model displays two arrays. Dragging the four points changes the arrays’ dimensions. The goal is to drag blue squares into the...
In my previous post, I presented an interactive Web Sketchpad model for visualizing and solving fraction multiplication problems. This week, I’d like to back up a step and focus on the more fundamental skill of visualizing and reasoning about the size of fractions. The fraction game below (and here) presents two random fractions at a time and challenges...