Sine of the Times Blog

Revisiting a Childhood Addition Code with Sketchpad

As a fourth-grader in 1977, I had a love-hate relationship with my Addison-Wesley textbook. Its contents overflowed with arithmetic problems, but every so often an entertaining brainteaser appeared to break the monotony of drill practice. These puzzles were clearly marked: Each appeared in a box set aside from the main text and featured a bespectacled...

Polar Graphing

Using Sketchpad, it is very easy to start from scratch and create a polar graph. Here are the steps to create the graph shown on the right below. Choose Graph | Plot New Function. Use the Equation menu to choose r = f(θ). Type “c” (for “cos”), “2”, and “th” (for “theta”). Click OK. If your angle...

Cartesian and Polar Graphs

The Web Sketchpad model below (and here) shows the function f(θ) = 1 – cos 2θ in both Cartesian and polar form. For each graph, the independent variable appears as a red bar that corresponds to a particular value of x (for Cartesian) or θ (for polar). The red bar has tick marks that show...

Exponential Harmony with Sketchpad

Last week was the fourth session of my spring Advanced Secondary Math Methods class at the University of Pennsylvania. Each year I assign a semester project in which groups of three students use lesson-study techniques—on a small scale—to create, test, refine, teach, evaluate, and document specific shared instructional products, composed of a (possibly multi-day) lesson...

A Swan Song for Sweet Karen Coe

Today I leave for my first proper vacation in a year and a half. Last time I took such a vacation, Key sold its high school textbooks to Kendall Hunt and transformed from a publishing company to a educational technology company. This time I just hope to survive the end of the world. 🙂 Before...

Pass the Candy! Sweetening the Study of Probability

As part of our guest blog series, we bring you another post from Kathryn Shafer. A former middle school and high school math teacher, Kathy is now an Assistant Professor in the Department of Mathematical Sciences at Ball State University, Indiana. She’s done a variety of work for Key, including presenting webinars, moderating online courses,...

Creating Origami Whirlpool Designs with Sketchpad

Tomoko Fuse is a Japanese origami artist whose designs are highly geometric. A Google search for her origami models reveals a plethora of boxes and intricate three-dimensional structures, many of which are folded from multiple sheets of paper and then assembled together. As an avid origami folder, I’ve always admired Fuse’s work. But nothing prepared...

ICME: The Nature of Students’ Mathematical Thinking

Like other enthusiasts of mathematics, I’m captivated by the way that mathematical ideas can explain things in the physical world around me, and by the way that I can carry out mathematical thought experiments in my mind and then apply the results to control my external physical environment. But it turns out that my separation...

ICME: A Sensory-Motor Experience of Korea

I had the immense good fortune this year to attend ICME, the International Congress on Mathematical Education. The Congress is held every year divisible by 4, and this iteration (the twelfth) was held in Seoul, Korea. It is quite something to be at a meeting of nearly 4000 mathematics educators from 84 different countries, and...

The Standards Are Not The Curriculum

We were so impressed by Jamila Riser’s talk at NCSM a couple of years ago that we asked her to present an Ignite! for us this year. Now, we’ve asked her to guest blog so we can share even more about the amazing work she’s doing in Delaware. Jamila is the Director of the Delaware...