I have been hearing good things about the Khan Academy - an impressive online education effort spawned by American computer scientist Salman Khan trying to tutor his cousin through screen capture videos. Khan has since quit his job in finance, is generously funded by Google and others and attracts 3.5 million monthly users. This mission is a test drive of KA as an education institution.

I picked the above video on Conditional probability and combination (watch it in the KA website for Q&As and goodies). I picked this because:

- math is the traditional area of strength of KA, and a traditionally badly taught topic in many countries including mine.
- probability theory is a very interesting and useful part of math, but many, myself included, find it counterintuitive and need to make a conscious effort to teach themselves to think in probability conditional probability is a topic I have been taught at university, but that I am not at all confident with. This means I can compare classroom teaching with KA, while still needing to learn the damn thing.

## How I did it

So how do you watch a video of a math lecture on the Internet? I armed myself with notepad and pens, just like in a normal classroom, and opted for a very active approach: this is math, and I like to scribble, not just to listen. As I dived in:**I made extensive use of the pause button**. Remember how you would scramble to keep up with the teacher? How you would need to make real-time decisions of whether to sit back and listen carefully (helps understanding) or scribbling frantically (helps memorizing) at any given time? That’s gone in KA. You can do both: you listen, pause the video and write down your notes. Missed something? No problem, just backtrack. The video never gets tired of repeating, so you can replay it until you get it right.- I took my time, and as a result spent
**about 30 mins to go through the video**(which is only 17 mins), while still going through all the steps myself and checking that I was getting the same results as the teacher. That’s super-cost effective, given that I am going through an example problem that combines conditional probability and combinatorics, with a great final two minutes of exploring the intuition of it at the end; and given that I spent no time at all traveling to a classroom. I guess that the one- or two-hour lessons we are accustomed to are the result of constraints imposed by the adoption of the classroom technology: teachers and students need to get there, take off their coats, take out their notes, find seats etc., and 15 mins are gone. At this point, you try to make the most of it by spending 40 to 100 minutes actually lecturing. KA videos use the topic, not the hour as a unit; most are 6 to 12 minutes long, at least in math. **what about questions**? You can ask them in the comments. And people do, and other people answer them. The quality is amazing! Here’s your peer-to-peer element in KA.**gamification**: KA awards points and badges for taking lessons, asking and answering questions. I got a “Nice Listener” badge for Probability because I watched more than 15 minutes of video in the same topic. :-)**added goodies**: there are transcripts for the whole lecture; the community is also involved in sharing notes and creating the subtitles in different languages