Getting 20 million points at Khan Academy

A few weeks ago I got my ten thousandth badge at Khan Academy and had decided to do something else in my spare time. But as things go I looked around some more, found some other exercises for which I did not have the Lightspeed badge ( 299,792,458 Meters per Second in the Earth category), found some exercises and new JavaScript material.

Then I did some rough calculations (11K for doing 100 exercises in a topic fast and correct, somewhat less than 1000 per video, and 1-2K for JavaScript exercises), and (g)estimated that the 20 million mark should be just in reach. Would that give me a second Tesla? Or even one of the other Black Hole badges?

As those who know me will guess (but probably still don’t understand), I had to try and find out.

Exercises: Lightspeed, Sub-light, Ludicrous, Ridiculous

On the way to the 20 million, I did slighly over 300 exercise topics up to the “Ludicrous” badge (100 in a correct in a row), achieving the Lightspeed with most, but not all of them. The difference with between the number of “299,792,458 Meters per Second” and “Sub-light speed” is now four (1058 vs 1062).

The differnce between Ludicrous and Rediculous is somewhat larger at ten (1065 resp 1055), which is a result of my tendency to take a break after the achieving the Lightspeed badge in a topic, and after coming back making a stupid mistake and then not feeling like doing 80 or more exercises just for the badge (there are no points attached with Ludicrous and/or Ridiculous, so they don’t help with the goal of achieving the 20 million, except for the 125 points earned per row of 5 answers).

Missed “299,792,458 Meters per Second” badges

For the initial 1.5 months or so that I was actively pursuing getting the 299,792,458 Meters per Second and Sub-light speed badges, I kept their numbers in sync, but at some point the system did not register achiving the one for “Addition and subtraction within 10”. I noticed because I tried and failed to get it show at the top of the badges earned list and I thought I missed having it show in the achievement pull down. (After the June 2014 redo of the layout, the badges page itself doesn’t show the totals anymore, but the descripancy between the sum of the earth badges there and the ‘home’ page count is still there).

One of the other missed badges was for the “Solving problems with similar and congruent triangles” exercise. I must say I hate those drag and drop exercises as it is difficult to get them done in at the right speed.

A similar “lack of speed” problem occured with “Solving problems with similar and congruent triangles”. Slightly more enjoyable than the drag and drop exercises, here you have to click so many buttons that I just did not get it done in time at some point. The timing constraint being especially frustrating because you have no clue if you are missing “the beat” if you retry going for Lightspeed as you already have the initial 4 speed badges, nothting shows up for 75 exercises and you migth be too slow...

The final missed Lightspeed is for the “Coin Flip” distribution. There I definately suspect a bug in judgement between biased coins and human guesses of them and after missing the badge several times after 50+ exercises done, analysing the mistakes and comparing them with correct answers I could not find a pattern in correct vs. incorrect judgements and gave up.

New formula input and other things slowing down answering

Halfway through my road from 15 million (or something like that) that I had achieving 10000 badges to the 20 million, the input of formula changed. So you can no longer type x**2 for the square of x, it has to be x^2. That did require some getting used to and is, although more easy to use when you start, IMHO slower than the old method when typing answers. I definetely think some already achieved badges would be out of reach because of speed constraints.

While doing the exercise on Benjamin Franklin, I got frustrated by another ‘Drag and drop” slowing me down. I tend to solve these by either dropping things at the front (pushing answers back, so selecting them in reverse order), or by dropping things at the end of the box (normally a longer mouse movement, taking time). However with the Franklin exercise the target box is small, resizes and things are very easily dropped at the wrong place, after which reordering is virtually impossible. I moved on to easier topics after getting frustrated with that one (only achieving “Going Supersonic”).


Not sure where to hold the draggable element to get it behind “Ambassador to France”

Notification pulldown

If you ever wonder (like I did), how many messages you can accumulate in the Notification pulldown next to your name, I got as far as 2500.

Scrolling through the list after getting the 2500, I noticed I had missed a few comments form people, so that was not such a good practise.

It is not that difficult to get up to 2500. I tried because I thought there was a limit at 1000 (one wrong click and the list is shown resettng to 0), but with 10 messages per topic exercised up until Ludicrous (12 if you do Persistence and Sticktoitiveness as well), they accumlate rather quickly.


Going to the movies

Watching videos to earn points is easier than doing exercises, as you don’t have to keep track of which videos you watched to completion as you do with what level of badges you got with the exercises. You can just look at the subjects and see if there are things missing from the unclosed graphics.

There are some frustration though as there are pointers to videos that cannot be watched because they are removed, so the list will show some unfinished business.

Finally 20 million

At some point I almost gave up, thinking there were no more exercises that I could do for Lightspeed badge (some I tried, but gave up on, not even achieving “Gettting up to Spped” and therefor not being able to do them in the required time limit).

But then I noticed additional JavaScript exercises (at 2000+ points each), and finally reached 20 million. I think I’ll finish the second JavaScript patch today, and then slow down a bit.


Achieving 10000 badges on 2014-07-03

Posted on 2014-07-04.