Parker Glynn-Adey

String Figure: Tartoruterjuk

Posted in string figures by pgadey on 2020/10/25

This is a traditional figure of the Arviligjuarmiut people. It is made near Kugaaruk, Nunavut. These instructions were adapted from: Mary-Rousselière, Guy. Les jeux de ficelle des Arviligjuarmiut. Ministère du Nord Canadien et des ressources nationales, 1969 p. 67.

  1. Form Opening A
  2. Thumbs picks up radial little finger strings.
  3. The indices pick up the ulnar thumb strings.
  4. Left thumb picks up distal radial string from right thumb.
  5. The right thumb releases its loops, and enters all three left thumb loops from the proximal side.
  6. The thumbs travel over all the strings and pick up the ulnar little finger string.
  7. Navaho the bottom three thumb loops.
  8. The thumbs get the distal ulnar index strings.
  9. Navaho the thumbs again.
  10. Release the little fingers.
  11. The little fingers enter the thumb loops from the proximal side, and catch the transverse string, hooking it to the palm.
  12. Release the thumbs.
  13. Navaho the indices and extend.
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String Figure: Jackhammer

Posted in string figures by pgadey on 2020/10/25

This figure was invented by Joseph D’Antoni of Queens, New York.
These instructions were adapted from String Figure Magazine Vol.6(4) Dec 2001 p. 15-17.

  1. Form Opening A
  2. Release the little loops.
  3. Rotate the thumb loop away from you, and place it on to the little finger.
  4. The right thumb enters the index loop from the proximal side and gets the radial little finger string and returns.
  5. Release the right little finger loop.
  6. The left index loop is transferred to the left thumb.
  7. The left little finger loop is transferred to the left index.
  8. The index loops are rotated towards you on to the thumbs.
  9. All the fingers enter both thumb loops from the distal side.
  10. Flex the strings back and forth to animate the Jackhammer


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Simple Stop Motion with ffmpeg

Posted in Computers, Uncategorized by pgadey on 2020/09/12

Andrew Lindesay has a nice script for simple script for using ffmpeg to do stop motion:

ffmpeg -framerate 10 \
-pattern_type glob -i '*.JPG' \
-vf scale=640:-1 -c:v libx264 -pix_fmt yuv420p \

This works great for compiling photos shot by a GoPro!
The shots are labelled chronologically by frame number:


So, the -pattern_type glob -i '*.JPG' argument picks them up in order.

The argument scale 640:-1 automatically resizes frames to 640xY and preserves the aspect ratio. This might not be what you want, but it makes for small videos.

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Heather Lynn Johnson: Create. Don’t Convert.

Posted in Teaching and Learning by pgadey on 2020/05/29

Foundational questions:

  • What do I want students to learn?
  • How can I curate a learning experience that takes advantage of this learning space?
  • What is feasible without creating something that is really text heavy?

Museum experience

Teaching playground:

  • Introduction (video: learning goals, objectives, human-engagement)
  • Investigation (classroom video, geogebra, interaction)
  • Reflection (how do I want people to engage with this? what do I want people to notice?)
  • Response (to the experience)

Freeze Frame Activity:

  • Take a screenshot
  • Give a title
  • Explain your title / choice

Recognize students device capabilities: phone, computer, etc.

Share directions on how to do stuff

Simplify, simplify, simplify.

Interview with Conway

Posted in Math, Uncategorized by pgadey on 2020/04/21

The Simons Foundation has a lovely series of interview with John Conway.
Lots of stories and insights. He lead a storied life.

John Conway

PreTeXt on Ubuntu 18.04

Posted in Computers, Math by pgadey on 2020/04/19

As part of the trying out new things bonanza, I installed PreTeXt. It turned out that my install was missing a couple packages: texlive-fonts-extra, texlive-science, and xsltproc.

Once these packages were installed, things worked great!

sudo apt-get install texlive-fonts-extra texlive-science xsltproc
git clone

cd mathbook
git checkout dev
cd examples/minimal/

xsltproc ../../xsl/mathbook-html.xsl minimal.xml
xsltproc -o minimal.tex ../../xsl/mathbook-latex.xsl minimal.xml
pdflatex minimal.tex

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P5.js Test-Run

Posted in Computers, geometry by pgadey on 2020/04/19

I played around with P5.js today. It is really nice software! There is an in-browser P5.js editor, so you can start playing around instantaneously.


function setup() {
angleMode(RADIANS); // Change the mode to RADIANS
createCanvas(200, 130);

function draw() {

v1 = [1,0];
v2 = [cos(PI/3),sin(PI/3)];


while (n <= 5){
while (m <= 5){
p = [20+(20*v1[0]*n)+(20*v2[0]*m), 20+(20*v1[1]*n)+(20*v2[1]*m)]

if ( (n*m) % 2 == 0){
fill(200, 0, 0);
} else {
fill(0, 0, 200);
m += 1;
m = 0;
n += 1;

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Bruce and Katharine Cornwell Films

Posted in Math by pgadey on 2020/04/08


Bruce and Katharine Cornwell produced beautiful animations of mathematics back in the 1960s. I watched the first couple minutes of their film “Possibly So, Pythagoras” (1963) and learned half a dozen pleasant things.

Check out their films, available on Vimeo here.

You can read the memorial from Reed College here.

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Ursula Franklin: Warrior for Peace by Stacey Gibson

Posted in Quaker by pgadey on 2020/04/07
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Lynne Dalgleish’s Mural

Posted in Advice by pgadey on 2020/04/06


Lynne Dalgleish‘s mural in the Annex.