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Khan
perseus
TypeScript2013–2017
Khan / perseus

perseus

Perseus is Khan Academy's exercise question editor and renderer.

6Distinct people
13Mentions
0Explicit recommenders
1.6KGitHub stars
REPOSITORY AT A GLANCE

What to know before exploring

What it is

Perseus is Khan Academy's exercise question editor and renderer.

GitHub

Where it is used

No documented product use has been verified yet.

What people are saying

No recommendation phrase was found in the indexed comments.

No classified warning is attached to this page. Read the discussions before treating silence as approval.

Also in these discussions

Mentioned in the same Hacker News threads. That is not proof they are substitutes.

This week on Hacker News

Nov 7–Nov 14 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/14/2026, 3:56:07 PM UTC.

No direct repository links were found in the indexed HN discussions over the past seven days. Older discussions are available below.

Mentions over time

HN mentions by year13 dated mentions

Observed mentions: 2013-06-05 17:27:56 UTC to 2017-05-23 16:55:33 UTC.

024682013-01-01 00:00:00 UTC to 2014-01-01 00:00:00 UTC (exclusive): 1 mentions; 0 submissions, 1 comments20132014-01-01 00:00:00 UTC to 2015-01-01 00:00:00 UTC (exclusive): 8 mentions; 0 submissions, 8 comments2015-01-01 00:00:00 UTC to 2016-01-01 00:00:00 UTC (exclusive): 2 mentions; 0 submissions, 2 comments20152016-01-01 00:00:00 UTC to 2017-01-01 00:00:00 UTC (exclusive): 1 mentions; 0 submissions, 1 comments2017-01-01 00:00:00 UTC to 2018-01-01 00:00:00 UTC (exclusive): 1 mentions; 0 submissions, 1 comments2017

Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.

View mention counts and date ranges
UTC ranges include their start and exclude their end. Select a period to filter the source evidence.
PeriodStart (UTC)End (exclusive, UTC)MentionsSubmissionsComments
20132013-01-01 00:00:00 UTC2014-01-01 00:00:00 UTC101
20142014-01-01 00:00:00 UTC2015-01-01 00:00:00 UTC808
20152015-01-01 00:00:00 UTC2016-01-01 00:00:00 UTC202
20162016-01-01 00:00:00 UTC2017-01-01 00:00:00 UTC101
20172017-01-01 00:00:00 UTC2018-01-01 00:00:00 UTC101

What Hacker News says

13 sources
Tom (the original author) wrote about that a bit: http://www.arguingwithalgorithms.com/posts/14-01-03-content-.... In general I think we want to do a lot of custom things, so we'd need a very deep integration with an existing CMS, to the point where the costs would probably outweigh the benefits. For example, we have our own editor for articles and exercises (https://github.com/Khan/perseus), which does lots of fancy things, so having a prebuilt editor wouldn't be useful, and in fact would be something we'd have to replace. Controlling the whole system is just simpler for us.
In Memcached-Backed Content Infrastructure at Khan Academy
1. If you're not passing the backbone models to React components, this sounds fine. backbone models as props ends up being really painful because of how mutable they are, and when we tried to manage that with mixins, it was buggy and caused problems (note: I'm not familiar with the actual mixin we used there and whether there was a better way to do it). Since most flux implementations are pretty stateful/mutable themselves, using mutable backbone models there, so long as you copy data out to pass to react views, seems safe. Though I'm excited long-term about the immutable flux implementations (https://github.com/rackt/redux) 2. We had a library originally written by Ben Alpert (now core react team) that handles all of our interactive svgs [1]. Since KA has a lot of legacy code there, and there hasn't been an immediate benefit to porting i
Read the rest
t (which would take a pretty significant time investment, on the [very roughly] order of a couple dev-months), this is still mutable jQuery/raphael code. There have been a lot of talks of eventually porting this to react, but the immediate need for it hasn't been there yet. However, I did write a React wrapper around much of this code which is used by newer interactive widgets [2]. [1]: https://github.com/Khan/khan-exercises/blob/master/utils/gra... [2]: https://github.com/Khan/perseus/blob/master/src/components/g...
In Khan Academy's React style guide
Khan Academy — Mountain View, CA (we also love interns, and remote is a possibility) We're a small, non-profit tech startup bringing a free, world-class education to anyone, anywhere. Here's a testimonial we received last week: ================================== I just want to say thank you a billion times to Khan Academy. My Geometry midterm was this Tuesday. I was worried, because I barely passed my Algebra one last year. Enter Khan Academy. It was great practice, as they had a good amount questions where you had to manipulate on screen variables, rather than just answer multiple choice questions. This stood out to me, as my school gives tests with these types of questions and no other review site i found had them. We got our scores back, and I was the only person in my class that got an A. It's not really an "inspiring" story, but hey,
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I figured I'd share it anyway. ================================== Mia might not think so, but her story does inspire and makes me happy to go to work here. Every month we get hundreds of letters like this from people in all walks of life who are thankful for our free, high-quality educational content. Most of you reading this are familiar with Sal's videos, but we also have hundreds of videos by other teachers, partnerships with organizations like MoMA and the California Academy of Sciences, and a huge library of interactive exercises. Over 20 million math problems are done every week on our site. A few things we're currently working on building right now: – Major improvements to our iOS app to let students practice skills on the go (or in a classroom with iPads!) [1] – Improved knowledge models so we can better know what you know and don't know [2] – Infrastructure improvements to make the site more reliable and faster for our millions of visitors every month [3] – Better tools for our content creators to allow them to make thousands of engaging, interactive exercise problems without knowing how to code [4] You'll be part of a small team working alongside both "celebrity" devs (like jQuery creator John Resig and Google's first employee Craig Silverstein) and many more who you haven't heard of but who are also really awesome. ================================== We're especially looking for mobile designers/devs but we have a handful of other positions open -- take a look and see if anything suits you. Apply at https://www.khanacademy.org/careers and mention that you're coming from HN. Feel free to ask me here if you have questions about applying or about KA in general. Unfortunately we can't sponsor visas right now unless you're from Canada, Australia, or Mexico. [1]: http://www.kasrak.com/writing/khan-internship/ [2]: http://mattfaus.com/2014/05/improving-khan-academys-student-... [3]: http://www.alangpierce.com/blog/2014/07/07/bigbingo-khan-aca... [4]: https://github.com/Khan/perseus
In Ask HN: Who is hiring? (February 2015)
Angular will force you to convert all your rendering logic into its declarative API: ng-if, ng-repeat, ng-include etc. With React, you can simply write your program logic in Javascript and compose, reuse and pass around parameterized components with ease. Try building a simple nested tree in both Angular and React to see how both feels. Khan Academy has open-sourced their QA builder that supports creating questions and answers with graphs, radiobuttons, multi-selects, images etc. It is built in React. Take a look here: https://github.com/Khan/perseus
In 2 years with Angular
Khan Academy — Mountain View, CA (we also love interns, and remote is a possibility) We're a small, non-profit tech startup bringing a free, world-class education to anyone, anywhere. Here's a testimonial we received last week: ================================== I am 52. I returned to school almost twenty years ago and did quite well--but I had taken care of all my math requirements 15 years before that and my degree is about as far from math as one can get. So I had not seen the inside of a math classroom for more than thirty years when I decided not long ago that I wanted to review high school math. Listening to Sal's explanations have made this so easy it is as though I had remembered all of it this whole time! I am disabled now, and have no means to continue formal studies in much of anything, but I am now learning the calculus and li
Read the rest
near algebra I was planning on studying when I was much younger--before my college career ran off the rails for an extended time. Thank you Sal (and the internets) for letting me remain a student! Keep this place running; I want to be able to hang around here until I am no longer able to hang around anywhere anymore. ================================== Every month we get hundreds of letters like this from people in all walks of life who are thankful for our free, high-quality educational content. Most of you reading this are familiar with Sal's videos, but we also have hundreds of videos by other teachers, partnerships with organizations like MoMA and the California Academy of Sciences, and a huge library of interactive exercises. Over 20 million math problems are done every week on our site. A few things we're currently working on building right now: – The next version of our personalized learning dashboard [1] to make the UI more consistent across subjects and to help people learn better – Improved knowledge models so we can better know what you know and don't know [2] – Infrastructure improvements to make the site more reliable and faster for our millions of visitors every month [3] – Better tools for our content creators to allow them to make thousands of engaging, interactive exercise problems without knowing how to code [4] – A major revision to our iOS app to let students practice skills on the go (or in a classroom with iPads!) You'll be part of a small team working alongside both "celebrity" devs (like jQuery creator John Resig and Google's first employee Craig Silverstein) and many more who you haven't heard of but who are also really awesome. ================================== We're especially looking for new product designers and mobile devs but we have a handful of other positions open -- take a look and see if anything suits you. Apply at https://www.khanacademy.org/careers and mention that you're coming from HN. Feel free to ask me here if you have questions about applying or about KA in general. Unfortunately we can't sponsor visas right now unless you're from Canada, Australia, or Mexico. [1]: https://www.khanacademy.org/about/blog/post/58354379257/intr... [2]: http://mattfaus.com/2014/05/improving-khan-academys-student-... [3]: http://www.alangpierce.com/blog/2014/07/07/bigbingo-khan-aca... [4]: https://github.com/Khan/perseus
In Ask HN: Who is hiring? (October 2014)
Khan Academy — Mountain View, CA (we also love interns, and remote is a possibility) We're a small, non-profit tech startup bringing a free, world-class education to anyone, anywhere. Here's a testimonial we received last week: ================================== I have been using your site for almost three years now. I am a 9th grade homeschooler who has always done okay in math, but I had some major gaps and lacked mastery in a lot of concepts, especially with fractions. Ever since I have started Khan, I have been able to go back and not only fill in those gaps, but master them. And now, fractions are one of the concepts I do best! This site is amazing and continues to get better every month. Thank you to Sal Khan, the Khan team, all its sponsors, and all its interns for making this site better and more available to all students from aro
Read the rest
und the world. Please keep doing what you are doing! ================================== Every month we get hundreds of letters like this from people in all walks of life who are thankful for our free, high-quality educational content. Most of you reading this are familiar with Sal's videos, but we also have hundreds of videos by other teachers, partnerships with organizations like MoMA and the California Academy of Sciences, and a huge library of interactive exercises. Over 20 million math problems are done every week on our site. A few things we're currently working on building right now: – Tons of improvements to our core learning dashboard [1] and predictive knowledge models [2] so we can better personalize a learner's experience – Infrastructure improvements to make the site more reliable and faster for our millions of visitors every month [3] – Better tools for our content creators to allow them to make thousands of engaging, interactive exercise problems without knowing how to code [4] – A major revision to our iOS app to let students practice skills on the go (or in a classroom with iPads!) - Expanding access for the billions of learners around the globe through various internationalization efforts You'll be part of a small team working alongside both "celebrity" devs (like jQuery creator John Resig, and Google's first employee Craig Silverstein) and many more who you haven't heard of but who are also really awesome. We're especially looking for new product designers (of all types) but we also have many engineering positions open as well as some positions for a teacher and contract question writers. Apply at https://www.khanacademy.org/careers and mention that you're coming from HN. Feel free to reply here if you have questions about applying or about KA in general. Unfortunately we can't sponsor visas right now unless you're from Canada, Australia, or Mexico. [1]: https://www.khanacademy.org/about/blog/post/58354379257/intr.... [2]: http://mattfaus.com/2014/05/improving-khan-academys-student-.... [3]: http://www.alangpierce.com/blog/2014/07/07/bigbingo-khan-aca.... [4]: https://github.com/Khan/perseus
In Ask HN: Who is hiring? (September 2014)
Khan Academy — Mountain View, CA (we also love interns, and remote is a possibility) We're a small, non-profit tech startup bringing a free, world-class education to anyone, anywhere. Here's a testimonial we received last week: ================================== Thank you Khan Academy for igniting the passion to learn everything which I usually neglected and missed during my academic carrier. Though myself should be blamed for that, the conventional classroom teaching and limited access of study material is also important factors. Now while teaching my students I am equally enjoying the materials. I sincerely hope Khan Academy should reach to every single child in the world. Thank you again for the magnificent en-devour. ================================== Every month we get hundreds of letters like this from people in all walks of life wh
Read the rest
o are thankful for our free, high-quality educational content. Most of you reading this are familiar with Sal's videos, but we also have hundreds of videos by other teachers, partnerships with organizations like MoMA and the California Academy of Sciences, and a huge library of interactive exercises. Over 20 million math problems are done every week on our site. A few things we're currently working on building right now: – The next version of our personalized learning dashboard [1] to make the UI more consistent across subjects and to help people learn better – Improved knowledge models so we can better know what you know and don't know [2] – Infrastructure improvements to make the site more reliable and faster for our millions of visitors every month [3] – Better tools for our content creators to allow them to make thousands of engaging, interactive exercise problems without knowing how to code [4] – A major revision to our iOS app to let students practice skills on the go (or in a classroom with iPads!) You'll be part of a small team working alongside both "celebrity" devs (like jQuery creator John Resig and Google's first employee Craig Silverstein) and many more who you haven't heard of but who are also really awesome. We're especially looking for new product designers (of all types) but we also have many engineering positions open as well as some positions for a teacher and contract question writers. Apply at https://www.khanacademy.org/careers and mention that you're coming from HN. Feel free to reply here if you have questions about applying or about KA in general. Unfortunately we can't sponsor visas right now unless you're from Canada, Australia, or Mexico. [1]: https://www.khanacademy.org/about/blog/post/58354379257/intr... [2]: http://mattfaus.com/2014/05/improving-khan-academys-student-... [3]: http://www.alangpierce.com/blog/2014/07/07/bigbingo-khan-aca... [4]: https://github.com/Khan/perseus
In Ask HN: Who is hiring? (August 2014)
At Khan Academy most of our frontend is now using React (including our personalized learning dashboard, coach reports, question editor [1], etc.) and we're really happy with it. We have about 750 React components and 50,000 lines of JSX now. We've migrated pieces incrementally and React is really great for doing that because it doesn't try to own your whole app. My friends and I also just launched Vim Awesome [2], which is not "large" but is completely written in React and is open source if you're curious to look at it. [1]: https://github.com/Khan/perseus [2]: http://vimawesome.com/
In React v0.11
A few things we're currently working on building: – The next version of our personalized learning dashboard [1] to make the UI more consistent across subjects and to help people learn better – Improved knowledge models so we can better know what you know and don't know [2] – Better tools for our content creators to allow them to make thousands of engaging, interactive exercise problems without knowing how to code [3] – A major revision to our iOS app to let students practice skills on the go (or in a classroom with iPads!) – Infrastructure improvements to make the site more reliable and faster for our millions of visitors every month [4] There's a ton more that we want to do but haven't had a chance to even think about yet. Not all of our work is technically interesting, but a lot of it is, and it's easy to find technical challenges if th
Read the rest
at's what you're looking for. (As for new content, we're working on partnerships with other organizations [5][6] and have many new content creators in other subjects [7]. We're obviously working hard to find ways to make more great content.) [1]: https://www.khanacademy.org/about/blog/post/58354379257/intr... [2]: http://mattfaus.com/2014/05/improving-khan-academys-student-... [3]: https://github.com/Khan/perseus [4]: https://twitter.com/soprano/status/474729636710985728 [5]: https://www.khanacademy.org/about/blog/post/90372763660/new-... [6]: https://www.khanacademy.org/about/blog/post/65072185996/khan... [7]: https://www.khanacademy.org/about/blog/post/89105955375/more...
In Ask HN: Who is hiring? (July 2014)
React is awesome. This weekend, I rewrote the Khan Academy exercise editor which looks like this: https://s3.amazonaws.com/uploads.hipchat.com/6574/26709/htv8... (The right side is a live preview of what's on the left. The editor is open-source https://github.com/Khan/perseus but not yet documented, sorry.) React made the code about 15% shorter and also made an order-of-magnitude improvement because it's smarter than I was being about figuring out what's changed and when it's necessary to touch the DOM. Of course, I could've made the same perf improvements by hand but it was easier and quicker having a library that just handles everything. (This comment sounds a little like I'm getting paid to write this. I'm not! Just really hope that React takes off.)
In Why did we build React?

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