Category Archives: computers

Abby’s Puzzles

My ten-year-old daughter asked me for help doing a mathematical STEM-fair project. We had a lot of funny doing the project together. Here is a brief description of what we did. We decided on the following question: “How many decominoes … Continue reading

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Radix sort with index cards

I showed my kids the radix sort.

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Math Camp I: Recursion and such

The past two years I’ve taught at a summer math camp for high school students. In 2010 I assisted with a class on chaos and fractals. This year I assisted with a computers class. I’m planning to do a couple … Continue reading

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Building a Computer 1111: Video of our Signal-Split Prototype

As I’ve said previously we are currently working on developing a signal-split device: that is, we want something that takes one input and creates a copy of it. Or in other words one marble in, two marbles out. Below is … Continue reading

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Building a Computer 1110: Video of the 4-bit Adder

As promised in a previous post, here is video of our 4-bit adder prototype. We used Wandel’s plans for it, but it is missing several niceties that Wandel’s version has: a top tray that holds marbles and releases them all … Continue reading

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Building a Computer 1101: Signal Split

I had an idea for a marble implementation of the signal split. It is very closely related to Wandel’s toggle. I ran the idea by my nine-year-old, then showed him the basics of Inkscape and let him do the drawing. … Continue reading

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Building a Computer 1100: Multiplication and Subtraction with an Adder

My nine-year-old has been playing with our prototype four-bit adder quite a lot. After getting bored with adding, he figured out how to do subtraction with it. Of course we talked about how to do subtraction earlier. What he ended … Continue reading

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