teaching machines

Goodbye, Positional Parameters

I dearly miss the year that I spent talking about shapes and math with elementary and middle school students through the lens of Madeup and 3D printing. Would that those days return! While I wait for the global health crisis to subside, I might as well fix a few bugs in Madeup—by reimplementing it without […]

Snap Circuits Bridges

We got my oldest son a Snap Circuits kit when he was very young. The product seemed like a great way to learn about electricity, but we quickly ran into the issue endemic to all educational technologies: you really need an informed human teacher to learn. We tinkered with the kit, but neither of us […]


I challenged myself to make a tulip in Twoville, and here’s my response:


I was challenged to make a raindrop in Twoville, and here’s my response: The exercise helped me fix an issue with mirror. Previously if the middle vertex was not on the mirror axis, I automatically inserted a straight line segment to bridge the gap between the mirrored segments. That produced more of a Hershey’s Kiss […]

Direct Tweaking in Twoville

A student and I working on tools for composing SVG files. The scenes are programmatically generated, but the geometric properties can be tweaked via direct manipulation. In other words, the user can drag on the shapes to modify both the scene and the source code. Consider the following program, which plots a rectangle. Select the […]

Kawaii Donut

During this time of staying at home, my family has not been able to get out and satisfy our sweet teeth as much as we would like. We have also been faithfully participating in graphic novelist Jarrett Krosoczka’s Draw Everyday with JJK on YouTube. JJK frequently profiles the work of his illustrator friends, and in […]

Modeling a Jump Sound

I recently unveiled Earpiece as a playground for exploring how sounds are shaped by their frequency and amplitude envelopes. Today we use it to explore a jump sound. First, close your eyes. Imagine you are holding a game controller. Press the jump button. Wrong one. Try again. That’s right. What did you hear? We can […]

Modeling a Coin Pickup Sound

Years ago I ran across sfxr, a little tool for generating sound effects. Seven classes of sounds can be generated: coin pickups, shots, explosions, powerups, hits, jumps, and blips. The author, DrPetter, made the tool to support folks like me who don’t have the time, skill, or team to make sounds for their games. But […]

Bathroom Angles

Our bathroom gave me a math problem, and I failed. Herein I document my failure and visualize the answer I should have provided. When we bought our home, the bathroom had carpet but no baseboard. This combination makes painting the walls difficult. As we are preparing to paint, I decided to install some baseboard. Measuring, […]

Cutting Corners

I learned recently of Chaikin’s Algorithm, a method for rounding off the corners of a polygon. The algorithm works like this: Find the midpoints of each line segment in the polygon’s perimeter. Connect each consecutive pair of midpoints using a quadratic Bezier curve. The midpoints are the curve’s endpoints. The vertex between them is the […]

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