marcia lee

there’s been a resurgence of greenpeace canvassers around the neighborhood, and these friendly folk share fun or frightening facts about the world and its imminent demise.

have 30 seconds to save the pandas?

sometimes i politely decline (even though i have nothing against pandas!), and sometimes i listen until the walk sign appears.

today, i saw another canvasser on the corner, and pre-empted him with what i had heard from his canvassing comrade the other day. he was taken aback, but then emoted “right on” with his smile.

i returned to my desk, looked up the veracity of what i had just said, and learned it was off by a factor of 1000.

goodbye!

Drum roll….
https://github.com/marcia/sesame
…cymbals, clash!

When users file issues on Khan Academy exercises, some information (the exercise name, the seed, and the problem type) is also sent so that we can reproduce the errant behavior.

Steps to open the referenced problem from the github issue page:
– Select info with cursor
– Copy info
– Open new tab
– Start typing beginning of “localhost/khan-exercises/exercises”
– Hit tab to autocomplete
– Paste info
– Hit enter

Steps involved with sesame:
– Type “o”

YAY!

P.S. It’s named “sesame” like “open sesame!” I thought my immense wit was obvious, but perhaps not so!

That was so easy! 900+ open issues is not daunting at all!

Behold, my first and possibly last Chrome extension!
https://github.com/marcia/subwayrepo

If you’re looking at a Khan Academy commit in Kiln that happens to have an obscure .hgsubstate change, a familiar leaf icon may appear to show the way. Click it to see the relevant GitHub commit message, click that pretty blue link to go to there.

Warning: This might have been created in the entirely Wrong Way, though I based it on this example and am using other people’s code.

In the past month, we’ve added 37 new exercises to our knowledge map! Did you notice these sneaky yet scintillating stars?

Fractions:
Adding fractions
Comparing fractions 1
Comparing fractions 2
Converting decimals to fractions 1
Converting decimals to fractions 2
Converting mixed numbers and improper fractions
Equivalent fractions 2
Expressing ratios as fractions
Ordering fractions
Recognizing fractions
Simplifying fractions
Subtracting fractions
Writing proportions

Inequalities:
Compound inequalities
Graphing inequalities
Inequalities on a number line
One step inequalities

Word problems:
Arithmetic word problems 1
Arithmetic word problems 2
Fraction word problems 1
Ratio word problems

Conic sections:
Recognizing conic sections
Equation of a hyperbola
Equation of an ellipse

Interesting:
Measuring angles
Telling time

Iterating:
Evaluating expressions 2
Exponents 4
Rate problems 0.5

Basics:
Comparing absolute values
Estimation with decimals
Number line
Ordering negative numbers
Place value
Properties of numbers 1
Properties of numbers 2
Recognizing rays, lines, and line segments

Huge thanks as always to our students, teachers, and contributors! It feels like the Khan Academy community grows bigger every day, but stellar teacher Courtney stands out in my mind for sending 13 PDFs of ideas and practice problems. Woo!

This past week has been a tortuous journey through the swampland of MathJax and Internet Explorer, turning unknown unknowns to known unknowns to known knowns and back again. If you haven’t heard of MathJax before, you just need to know that it powers all the beautiful math in Khan Academy’s exercises, and it doesn’t always work in IE.

The latest hypothesis is that folks using Windows with guest accounts using Internet Explorer will NOT be able to use MathJax. It boils down to the fact that request headers do not include:

Accept-Encoding: gzip, deflate

…while the response headers do include:

Content-Encoding: gzip

I don’t understand why Internet Explorer is being difficult only for guest accounts, nor do I understand why MathJax isn’t accommodating. I also don’t get why Internet Explorer insists on:

HTTP/1.0

…when I have very clearly checked the “Use HTTP 1.1″ checkbox and pressed the required number of “OK” buttons to indicate that I really know what I’m doing.

We’d seen a few “Problems aren’t showing up” bug reports, but since we always tested the site with an administrator account, we never encountered this particular flurry of doom. A bug report from a helpful user saved the day. (THANK YOU, helpful user, if you are reading this! Also, THANK YOU @mrawde.) By the way, this info is partly described in this thread, but of course fate didn’t let me find that discussion until the very end.

Out of completeness, here are some earlier (and still valid) ideas of why MathJax was not able to execute its tagline of “Beautiful math in all browsers.”

• The most relevant part of the MathJax FAQ on IE was that the font download setting should be enabled (for web fonts to work). Since MathJax will wait 5 seconds before considering the web fonts to have timed out, I thought people might’ve been impatiently reporting bugs when the image fonts were already on their way and going to appear imminently. Now, if you’re an IE user who hasn’t enabled this setting, you’ll (eventually…) get a message telling you to do so.
• A few users had also reported unresponsive script errors, and the only way I could reproduce that was to throttle my Internet (it turns out that our flaky office network is reasonably fast… when it’s not down). It seemed like MathJax wanted to Do Stuff when the files hadn’t completely loaded, so now MathJax just quits completely after a slightly more forgiving timeout. This doesn’t fix the problem for people whose Internet consists of butterflies passing messages through the rhythmic flapping of their wings, but at least their browsers don’t crash and now they get a message telling them to refresh and hope for lower latency.
• Last but not least, school networks tend to block the Internet, including benevolent domains like mathjax.org. We now check whether you’re blocked from accessing MathJax’s favicon, and, if necessary, we tell you to ask a “network administrator” to unblock appropriately.

The highlight of this fearless adventure was that I finally downloaded Charles, and I had a lot of fun learning how to use it. It was not so fun increasing my network latency and working with Internet Explorer + its “developer tools” in Fusion. It was also not so helpful that documentation would mention “15 seconds” but the real unit in code was milliseconds, or that font warning extensions didn’t actually display all relevant warnings. But that’s okay! Despite my curmudgeonly complaining, this was all fairly enjoyable. :)

Please ping me if I’m missing another root issue, or if you know of a quick easy fix for the whole gzip thing! This link probably works the best: http://khanacademy.org/jobs

:: edit :: The fellows at MathJax are super nice and responsive, and the main point described in this blog post is now irrelevant! Yay!

If you are using Internet Explorer and math expressions on Khan Academy exercises take a while to load, consider following these steps to improve exercise speed and appearance.

Open the Tools menu and click on Internet Options.

Click on the Security tab and then click on the Custom level… button.

Scroll down until you find the Downloads section, and enable Font download.

Celebrate! Math should appear more quickly, and now you will enjoy the benefits of seeing different colors! (Contrast the blue and green numbers below with the first screenshot)

read this if you are not 100% familiar with the codes and you’re wondering how to view an exercise locally.

step 1a: download github for mac. http://mac.github.com/

step 1b: while waiting for the completion of step 1a, compare error pages.

exhibit 1. https://github.com/marcia_is_awesome

exhibit 2. http://www.khanacademy.org/exercises?exid=marcia_is_awesome

step 2: visit https://github.com/Khan/khan-exercises/ and click on “Clone in Mac”.

step 3: wait for the khan-exercises folder to sync.

step 4: you can click on khan-exercises and see the latest commits. press “Sync Branch” whenever you want to get the latest work we’ve done.

step 5: open the exercise file (for example, khan-exercises/exercises/addition_1.html) in firefox. it is important that you use firefox, since it won’t work in chrome unless you do a few more extra steps that i don’t remember off the top of my head. note that if you’re viewing the exercise in this way, you will lose the color highlighting of math text. (the 7 and 8 below are actually blue and green, respectively.)

step 6: celebrate! take a peek at what we’re working on, send feedback, and feel like a hacker.

step 1: find the right menu! it will either say “Tools” or have a wrench icon.

step 2: open the menu.

step 3: find “Developer tools” and click it!

how it looks in ie8:

how it looks in ie9:

step 4: check out that new window that popped up. click on the “Console” or “Script” tab.

step 5: good job! time to celebrate.

debugging internet explorer problems over email is not the most straightforward of processes, but one does what one can.

inspired by ben’s summer internship post and jason’s redesign post, i figured i would ease back into this blag with more show and less tell. and now the exercise team presents…

since the huge exercises rewrite, we’ve been adding new exercises to fill in the gaps and expand our mathematical horizons. above is the student progress from kami’s class at the end of last school year, and we’re racing to keep the number of uncompleted exercises non-zero. :)

we’ve tried our hardest to banish multiple choice from our exercises, demanding even more of our students…

…and we communicate our stricter expectations.

but once you get the hang of it, we won’t belabor the point and let you hide acceptable answer formats.

screenshots don’t depict interaction very well, but it’s undeniable how much faster it is/feels. hooray for not re-loading the page to get the next problem! instead of the whole site blinking at you, the next problem just fades in.

check out that protractor! i can’t wait for exercises to become more and more interactive.

before, we didn’t pay attention to the number of hints available, but now we gray out the button when you’ve revealed all the hints.

not to be a copycat since ben and jason both had “join us” blurbs at the end of their posts, but yes, we’re hiring! our First Ever Class of Interns got these amazingly cute gifts in appreciation of their Amazing Selves, and let that be the straw that forced you to visit khanacademy.org/jobs.

when you apply, please specify which blog was the most convincing. :)

shout out to the great and growing list of contributors!