Khan Academy

7 Mar 2018

Khan Academy is a non-for-profit organisation based in Silicon Valley. Its mission statement is to provide a free world class education for anyone anywhere. It started with Salman Khan making maths videos for his cousin, but has expanded to have thousands of videos and exercises covered a whole range of topics, with a whole platform of tools for students and teachers.

I worked as a freelance content creator for Khan Academy from April 2014 to November 2017. I still work for Khan Academy indirectly, building the content for their partnership with Pixar.

Becoming a freelancer

After spending a lot of time on the Khan Academy website, answering students' questions, winning a couple of coding competitions, and building an app that used its API to track how close students were to achieving various badges, I was invited to their offices in Palo Alto. At the time I was working as a molecular and cell biologist in a marine biology lab, but my contract was only a few months from ending. When Khan Academy offered me the chance to become a freelance content creator I decided to leave the world of science and give it a go.

Screenshot from modeling accretion disks

A program I wrote to model accretion disks for a Khan Academy coding competition. Sal even made a video about it.

Maths exercises

Initially I worked on building maths exercises on Khan Academy: creating code to randomly generate questions, answers and hints. I was particularly involved in building a system to represent rational expressions, so the correct steps for simplifying rational expressions could be generated. I was in charge of maintaining the maths exercises for a year or so before, they replaced the whole system with static questions written by teachers.

One of my favourite exercises was a series of questions on compass constructions. Students were given the ability to add straight lines and circles to a diagram and asked to create various construct: parallel lines, bisectors, inscribed shapes etc..

For this I was working with a pre-existing library for generating interactive elements, which inspired to me to later make my own.

Example of a compass construction exercise on Khan Academy


Later I worked on building interactive explorations for Brit Cruise's lessons on magnetism and electricity. These lessons comprised videos with no words, showing how someone might rediscover magnetism for themselves and build a simple battery.

Field lines for a magnet in 3D

Interactive explorations


Later I worked on building all the interactive elements for the Khan Academy's partnership NASA. When the partnership with Pixar: Pixar in a Box, was launched, I was in charge of creating all the interactive content and most of the exercises. I have now moved to being on the Pixar side of the partnership.

Comments (8)

Nicholas on 2 May 2018, 11:40 p.m.

This is Nicholas from Khan Academy.
This is very great! I don't really have any suggestions right now, but it is looking good so far.

Malachi KA on 28 Aug 2018, 10:46 p.m.

This Malachi from KA @mz2x
this blog is amazing Peter are you still updating it :)

Reid Pelton on 21 Feb 2019, 2:21 a.m.

With the new Khan Academy API, What Badge Next no longer works. Nearly all of the links are broken. Have you abandoned the tool completely?

Peter on 22 Feb 2019, 8:35 p.m.

Yes, sorry, I abandoned WhatBadgeNext long along. I'm not sure I can even remember how to get the code for it.

Phneas Greene on 11 Jul 2019, 2:14 p.m.

Nice site! You should feature some of your great just for fun games like Hacker Puzzle and The Janitor of Glinar TeK.

Peter on 13 Jul 2019, 10:24 p.m.

Thanks Phneas. I have written a little bit about some of my games here:

Arnav @CrazyTrain1 on 30 Jul 2019, 1:49 p.m.

Mr. Collingridge sir, I have heard about you from lots of KA users. I use your APIs (I was first introduced to them by Anton van der Neut). I still sometimes use WhatBadgeNext. All I want to say is, you are an amazing person who makes dreams come true. Thank you.

Gabe Culpepper on 30 Jan 2020, 5:03 p.m.

Man Peter, you worked for NASA? Well, not directly, but still. When I was in 3rd grade (3 years ago) I thought NASA was lit, but working for them? Duuuuude! And Pixar: Pixar in a Box? Swagger gotchu dude. Livin' dat dream life cous. I know I sound black (no offense to anyone who is black or white, so don't hate me) but I am white. But for real man. Those guys are lit. How'd it feel bein' with em'?