Author: Daniel Scher
Stars, Polygons, and Multiples
I’ve always found my collaborations with teachers to be a great inspiration for curriculum development, and that was especially true of my work with Wendy Lovetro, an elementary-school teacher in Brooklyn, NY. Wendy coordinated an after-school math club at her school, and I used the setting as an opportunity to develop and field test Sketchpad activities for the...
Raz’s Magic Multiplying Machine
Here is a question you don’t hear very often: What does it feel like to experience multiplication in our bodies? It’s a strange question because our typical exposure to multiplication is numerical. I give you two numbers—say, 3 and 5—and you tell me their product, 15. But multiplication need need not be so static and concrete....
Pythagoras Plugged In
The title of this post is a nod to the Sketchpad activity module Pythagoras Plugged In by Dan Bennett. Dan’s book contains 18 visual, interactive proofs of the Pythagorean Theorem. And there are more: The Pythagorean Proposition, published in 1928 by Elisha Scott Loomis, contains over 350 proofs, 255 of which are geometric. Wow! I revisited the Pythagorean...
Adding and Subtracting on a Dynamic Number Chart
Below (and here) is a collection of four interactive number charts that we first introduced in our NSF-funded Dynamic Number project. Start by asking students to press the four directional arrows and to explore what they do. The right arrow, for example, moves the shaded square to the right, and wraps the square to the next row up...
Estimating Angle Measurement
Angles are a thorny concept to teach because of the fundamentally different ways in which they can be used and understood. In the article What’s Your Angle on Angles?, the authors divide the concept of angle into three main groups: angle-as-figure, angle-as-wedge, and angle-as-turn. In the Web Sketchpad game below (and here), we focus on angle-as-turn. Given an angle, students...
An Equivalent Fractions Game
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...
A Compendium of Elementary Web Sketchpad Activities
Below is a complete list of all the interactive elementary-themed activities we’ve offered on our Sine of the Times blog. Most of these activities grew out of the work that we did during our NSF-funded Dynamic Number project. The list includes links to our original blog posts as well as links, in brackets, that take...
Comparing and Identifying Fractions Visually
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...
Understanding Fraction Multiplication
Last week, Scott and I attended a fraction symposium at NYU, and it made me realize how long it’s been since I’ve written about our Sketchpad work with fractions. Below is a Web Sketchpad model for displaying and solving fraction multiplication problems. Representing fraction multiplication with an area model is a common approach, but it’s challenging to sort...