7 ms·

Need to refresh your math skills? From basic algebra to calculus and beyond.

344 points by chaosmachine 17y ago

chaosmachine 17y ago
I found this while doing some research on collision detection algorithms. All math classes should incorporate game programming, I sure would have paid more attention.
- RiderOfGiraffes 17y ago
  Isn't this a classic case of "What works for me must work for everyone." ?? Not everyone is interested in games, not everyone is interested in programming. One source of motivation should not be forced on everyone, there should be a wide range.
  - chaosmachine 17y ago
    Possibly. Any "real world" application would have been better than just theory. But games seem like a natural extension of math lessons, and who doesn't like games?
    - dutchflyboy 17y ago
      I agree, it's not a case of "What works for me must work for everyone" but more a case of "applying theory helps learning, especially when it's fun". I still haven't found anyone who doesn't like any game, so as long as there are a few different possibilities it DOES work for everyone.
    - nailer 17y ago
      Agreed. I remember learning trig at high school, without any motivation being presented whatsoever. Just 'lets calculate what this equation looks like' - what it came time to the government mandated project, there was a practical use - graphing the movement of a pendulum clock - which made it much easier to learn. And yes, who doesn't like games?
    - RiderOfGiraffes 17y ago
      Well, just to provide a single example, my wife is totally disinterested in games. Absolutely doesn't care, to the point where if someone tries to motivate topic X via games she ends up feeling that topic X cannot have any value to her at all. By contrast, she is very interested in math, and wishes that at school it had been presented as other than a collection of facts to memorize and processes to learn and apply. I know of others who have a similar attitude to games, and now, as I approach 50, I can't care much about them either. Games aren't "Real World." If you want "Real World" motivation then find some stuff from the real world. To add some context, I am passionate about putting things in context and making them relevant. I visit schools to talk about uses of math, and explaining how these subjects are anything but isolated and irrelevant stuff to learn and hoops to jump through. I've given talks in venues such as the West Yorkshore Playhouse, the Royal Exchange in Manchester, the Criterion Theatre in the West End of London, Navy Pier in Chicago, and others around the world. I give examples from GPS and SatNav through intercepting drugs couriers and on to gene splicing and DNA analysis. I talk about finding cliques and connections in social networks, and then apply that to detecting plaigarism and ranking web sites. I talk about weather forecasting, roulette, life assurance and debt management. I mention them in passing when relevant, but I don't talk much about games.
      - oscardelben 17y ago
        At school, usually the vast majority of people is interested in games. Of course you can never satisfy everyone, but that's not a good reason IMO to not do anything just because a few people might not like it.
        RiderOfGiraffes 17y ago
        > At school, usually the vast majority of people is interested in games. "People" or "boys" ?? I'd be interested to know your basis for your assertion, and now that the question has been raised I'll start taking informal polls as I go out and give talks. I do about 90 talks a year, and I'll see what the feedback is. And in what aspect of games? Being interested in playing various games is not the same as caring how they work, or caring about the idea that math is used in them. I'm not saying that games can't or shouldn't be used as motivation, but I have grave doubts as to the ubiquity of the appeal that people here seem to be taking for granted. To some extent it's the extremity of the view to which I'm objecting. chaosmachine earlier said: > All math classes should incorporate game programming I really can't believe that such an extreme view is a good thing. It would be akin to saying: Actually math isn't interesting in its own right, we really just need it to write really cool games. Leaving aside that particular comment, I still think that tying math only to applications is a bad thing. Motivation is essential, yes, but sometimes there's math that arises from the math, and only finds application much later, if ever. In short, my personal feeling is that you're wrong that the vast majority of kids would be motivated by games, but I have no stats to back that up, just 25 years of giving talks to school kids. Majority, maybe. Substantial proportion, probably. Far better to get the motivation by using math in a wide, wide range of applications. It's motivation at all, and the sheer breadth that really matters.
  - deleted 17y ago
    [deleted]
  - Skriticos 17y ago
    I agree. The most effective method would probably be to select various topics of practical usage for maths. That way the likelihood of finding interesting topics for all at one point or the other would increase very much. This would also help the kids to get a little more perspective of how the world actually works, which might benefit them.
ahlatimer 17y ago
I used their videos on youtube while taking a linear algebra course last semester when I needed an extra lesson on a particular topic. I highly recommend them. Everything I saw was presented in a clear, well articulated matter that made it much, much easier to understand than just reading something out of a book.
- SandB0x 17y ago
  His videos. They were all created by one guy.
- Tim_M 17y ago
  I have not tried his videos yet but I would highly recommend http://www.youtube.com/user/patrickJMT#g/u http://www.youtube.com/user/patrickJMT#g/u also.
ivan_ah 17y ago
Salman Khan is an extremely talented teacher. I would go as far as to say he is Feynmanesque in his ease with the subjects and ability to come up with good examples for abstract concepts.
edw519 17y ago
With just a computer and a pen-tablet-mouse, one can educate the world! I'll say. Someone's been very busy. Thank you, Khan. This appears to be an excellent resource. The 10 to 15 minute "bite-sized" pieces make it easy to check something out in your spare time. Most definitely bookmarked. I also like how he has added a lot of business/finance stuff, which should probably interest a lot of people here. Looks like a slight change of plans today - I have to check more of this out. [EDIT: I watched several videos in the Venture Capital and Capital Markets section. Definitely worth my while. This teacher appears to be able to make any topic, regardless of complexity, easy to understand. He even has a "happy cursor", which reminds me of football quarterback Peyton Manning's feet when he's getting ready to throw a pass. Funny how you can tell when an expert is in the zone. I'm going to put together a schedule to watch a whole bunch of these videos.]
coffeemug 17y ago
I found that the best way for me to internalize a particular subject in hard science is to follow its history by reading the original papers. It's a hard way to do it, but it helps you understand the motivation, the progression of ideas, and the rigor that went into it. Anything else doesn't quite work for me - I feel like I "sort of" understand, but five minutes after I close the textbook (or the YouTube video) the understanding goes away with it. I watched some of these lectures - they're excellent, but a bit too hand-wavy. Without getting through the rigor there's no hope to gain a complete understanding of the subject matter that stays with you forever.
- plinkplonk 17y ago
  "I found that the best way for me to internalize a particular subject in hard science is to follow its history by reading the original papers." I've often wondered why math programs (and books) aren't structured this way, explaining the historical context, reproducing the original papers (or explaining the arguments or proofs in the paper if the original happened to be in Latin or whatever), with a section on how the paper helped move the field forward and so on. It doesn't necessarily have to sacrifice rigor to do this, and a s amatter of fact I suspect a "walk the path (taken by the innovators)" approach coupled with strict rigor would make for some awesome books (and get more people interested).
  - RiderOfGiraffes 17y ago
    Frequently the historically motivated path is too long or creates too much baggage. It's not always the case, granted, and sometimes the historical development does give you the motivation, but you're still asking for a gifted teacher, and that's rare. A gifted teacher can teach with or without the historical perspective, and in my experience a clean, direct presentation with appropriate motivation and context is usually better. Again, not everything works for everyone.
    - plinkplonk 17y ago
      "but you're still asking for a gifted teacher, and that's rare." Fair enough. Maybe a gifted teacher can write a book :-) "Again, not everything works for everyone." I agree. There are a lot of texts which ignore the history. It would be great to have a few which retraced the paths.
billswift 17y ago
Buying good textbooks to learn from is a lot more cost effective than spending on the high-speed internet connections that is needed to download even a short video in any reasonable time. This "resource" is only useful to already have high-speed internet access.
- chaosmachine 17y ago
  A month of high speed internet is cheaper than a single text book in many countries. Considering there's probably 40 textbooks worth of material on this one page alone, nevermind the rest of the internet, I'd say priorities should be on providing internet access.
  - argv_empty 17y ago
    That and high-speed internet may be a sunk cost anyway.
  - pbhjpbhj 17y ago
    OLPC + Khan Academny videos = win.
    - GFischer 17y ago
      Only if they were in Spanish - here in Uruguay we have the OLPC deployed for all schoolchildren, but most students don't have the level of English required :)
      - pbhjpbhj 17y ago
        Well your Spanish is good ...?! It's not a huge stretch to imagine someone sitting and redubbing one of these though is it?
        GFischer 17y ago
        Well, it sounds like a long project to me :) . It would be a nice project, though, maybe I'll propose it (and contribute to it). Guess the first step would be contacting Khan. PD: Spanish is my mother tongue.
scrrr 17y ago
Excellent website, I'm impressed.
pixcavator 17y ago
I like the style and I appreciate the idea. In fact, I’ve been working on something in the same direction. So, here are a couple of things that I prefer to do differently. First, these are video lectures but without actual students present. As a result, he is essentially talking to himself. I noticed that this causes him to skip some details that students might be wondering about. I prefer to start with actual lectures and initially put them on the web as pdfs (http://users.marshall.edu/~saveliev/Teaching/Fall09/m430/updates.html http://users.marshall.edu/~saveliev/Teaching/Fall09/m430/upd...). Then I transcribe them to an online version (http://inperc.com/wiki/index.php?title=Introductory_algebraic_topology:_course http://inperc.com/wiki/index.php?title=Introductory_algebrai...). This is the second problem I have with his approach. Video just isn’t enough. I don’t’ have to explain to you what video doesn’t have and html does: searchability, cross-linking, speed of download, the ability to read and work at your own pace, etc. Certainly, my way is much slower.
- pyre 17y ago
  One thing that video has that HTML doesn't: single-file archive ability. Sure you can have a single HTML file as long as you keep it text-only, but most of these topics are going to be diagram (and math figure) heavy. There's just no good way to archive the content for later perusal. (Granted YouTube doesn't want you to directly download the videos, but it's not like it's that hard to circumvent -- and once you have the video you can easily find a player for it on any platform) [Note: I don't count .webarchive or .mht files as 'good enough'. .webarchive files are Safari-only, and I don't even know of a tool to be able to extract data from them. .mht files are 'sorta' supported (IE, Opera, Firefox w/ an extension), but I don't like the idea that the data is Base64/MIME-encoded. Personally I like .maff (Mozilla Archive File Format). It's only supported in Firefox with an extension (and nowhere else unfortunately), but it's basically a Zip file with the HTML/CSS/images inside of it.]
  - pixcavator 17y ago
    Well, the site runs on MediaWiki, so you can save the printable version of each article. Even if you print the whole thing, the end result wouldn't be that much different from a bunch of video files for each 15-min lecture.
NyxWulf 17y ago
For most people, they come out of high school not just poor at math, they come out "Math Broken" as one of my friends puts it. The second you mention anything to do with Math, their eyes glaze over and their brain completely disengages. I think there are a lot of things that contribute to that, but generally Math is not taught in a very approachable way. The KhanAcademy is I think a very good start in solving that problem. I came across this site through an article that was on HN sometime last year, around November or December IIRC. Since then I've watched roughly 100 videos on that site. Some of the Finance videos, Trig, and Pre-algebra as a refresher, and I'm now roughly 60 videos into the Linear Algebra videos. Even though I'm in the midst of my master's program now, I've set a goal to watch 2 video's every day as time permits. I am so impressed with this site, and with Salman Khan. The math is very well done, but it's also very approachable. Most of the videos are roughly 10-15 minutes in length and are highly topical. That makes it easy to jump in and pick up a refresher on something you haven't seen for a while. It's also great for getting into something you haven't ever seen before. Personally I haven't ever had Linear Algebra before, and if you've looked at many of the textbooks, they are pretty dense, particularly if you are self learning. I've found this site to be a great resource in getting oriented and it has really helped me get some traction. I have recommended this site to dozens of people, and while most of them don't share my love of mathematics, they have been able to get some traction in various problems by using this site as a supplement. Anyway, as a daily user of the KhanAcademy, I can't say enough good things about the site. I don't think it's a stretch to say it has the potential to revolutionize how math is taught. The one downside to the site I've noticed is the lack of problems sets. There is a tester that will walk you up through the different topics, but unlike the video's you can't just start where you feel you need to, you have to work up through the early material, and that's fairly time consuming. I have a number of other resource's I'm using for problem sets, but it would be nice to have a few problems to work through for each video. Overall an absolutely fantastic resource. Rating: 10/10
- RiderOfGiraffes 17y ago
  I agree with everyone else that it's a fantastic resource and the material is brilliantly presented, but I don't think it will help with the "Math Broken." I'm absolutely not knocking the resource or the site, I can't say enough good things about it, but if someone is already glazed over at the very mention of math, I don't think the videos here will help. If you think otherwise then I'd really appreciate a suggestion, as I have someone I'd like to point at it ...
sscheper 17y ago
Wow, that's some deep material. Thanks for the link, Chaos.
rick_2047 17y ago
This thing really could have helped me prepare for chemistry for exams in school. I matches my curriculum to the mark. definitely going to share with my juniors.
3dFlatLander 17y ago
I'd like to add a very personal comment to this discussion. I have very bad vision. So much so that in school, I couldn't see the board even when sitting as close as possible. As a result, I'd end up creating notes from a synthesis of what the teacher was saying and what I read in the book as the lesson was going on. This usually didn't work out, and my math skills suffered. This website helped me fill in the gaps of knowledge I had. Actually being able to see the problem being done while given instructions was a great help.
jasonlbaptiste 17y ago
I make this comment every month: There needs to be a comprehensive site that aggregates all the educational videos on the net (lectures, conference talks, screen casts, simple instruction,etc.).
- hexis 17y ago
  For better or worse, that site is google.com
  - jasonlbaptiste 17y ago
    It's a start, but there needs to be 1000x better organization and curation.
- mmelin 17y ago
  I think that http://academicearth.org/ http://academicearth.org/ does a good job, although they only aggregate courses from universities.
- lunchbox 17y ago
  Try http://nalandau.com/ http://nalandau.com/
- NalandaU 17y ago
  We took an initial stab at this and aggregated about 10K videos, and give tools to take notes and tests. Eventually we plan to extensively integrate text contents from Wikipedia, OpenCourseWare etc along with these videos. We are a very young website and would love to get feedback on what are the other resources you guys looking for: http://www.nalandau.com/course/8/programming-(10) http://www.nalandau.com/course/8/programming-(10) regards, Balaji Viswanathan, Founder, NalandaU.com
Slashed 17y ago
My math skills were always bad. I mean, even though I had one of the best scores in school, I could never explain why it works, e.g. why 9^1/2 is the same as sqr(9). Since I want to self-study the Quant Finance, I decided to refresh and develop my math skills up to the Calculus. This website is amazing! Not only it's a good refresher, it's the best source of knowledge created by one man.
- eru 17y ago
  Interesting. I usually learn best by explaining / teaching.
morphir 17y ago
I feel the need to point out that when I submitted a link to khan academy, no one up-voted it. Why is this? ref. http://news.ycombinator.com/item?id=911882 http://news.ycombinator.com/item?id=911882
- onoj 17y ago
  I did not see it that time? May also be the title given to the post. Humans are fickle. ( will up vote you now ;)
- teeja 17y ago
  I'm guessing it was the word 'youtube' combined with 'educate'. (Youtube doesn't have much, uh, 'patina' for some of us.)
rubyrescue 17y ago
How sad that people pay up to 40k to the University of Phoenixes out there, or, worse, take on 40k of unforgivable and practically un-repayable federal student loan debt, when this type of material is available for free!
oPerrin 17y ago
Unfortunately decimals seem to be harder for computers than people :) http://screencast.com/t/ZjUwOWRl http://screencast.com/t/ZjUwOWRl

344 points by chaosmachine 17y ago

I found this while doing some research on collision detection algorithms. All math classes should incorporate game programming, I sure would have paid more attention.

RiderOfGiraffes 17y ago
Isn't this a classic case of "What works for me must work for everyone." ?? Not everyone is interested in games, not everyone is interested in programming. One source of motivation should not be forced on everyone, there should be a wide range.
- chaosmachine 17y ago
  Possibly. Any "real world" application would have been better than just theory. But games seem like a natural extension of math lessons, and who doesn't like games?
  - dutchflyboy 17y ago
    I agree, it's not a case of "What works for me must work for everyone" but more a case of "applying theory helps learning, especially when it's fun". I still haven't found anyone who doesn't like any game, so as long as there are a few different possibilities it DOES work for everyone.
  - nailer 17y ago
    Agreed. I remember learning trig at high school, without any motivation being presented whatsoever. Just 'lets calculate what this equation looks like' - what it came time to the government mandated project, there was a practical use - graphing the movement of a pendulum clock - which made it much easier to learn. And yes, who doesn't like games?
  - RiderOfGiraffes 17y ago
    Well, just to provide a single example, my wife is totally disinterested in games. Absolutely doesn't care, to the point where if someone tries to motivate topic X via games she ends up feeling that topic X cannot have any value to her at all. By contrast, she is very interested in math, and wishes that at school it had been presented as other than a collection of facts to memorize and processes to learn and apply. I know of others who have a similar attitude to games, and now, as I approach 50, I can't care much about them either. Games aren't "Real World." If you want "Real World" motivation then find some stuff from the real world. To add some context, I am passionate about putting things in context and making them relevant. I visit schools to talk about uses of math, and explaining how these subjects are anything but isolated and irrelevant stuff to learn and hoops to jump through. I've given talks in venues such as the West Yorkshore Playhouse, the Royal Exchange in Manchester, the Criterion Theatre in the West End of London, Navy Pier in Chicago, and others around the world. I give examples from GPS and SatNav through intercepting drugs couriers and on to gene splicing and DNA analysis. I talk about finding cliques and connections in social networks, and then apply that to detecting plaigarism and ranking web sites. I talk about weather forecasting, roulette, life assurance and debt management. I mention them in passing when relevant, but I don't talk much about games.
    - oscardelben 17y ago
      At school, usually the vast majority of people is interested in games. Of course you can never satisfy everyone, but that's not a good reason IMO to not do anything just because a few people might not like it.
      - RiderOfGiraffes 17y ago
        > At school, usually the vast majority of people is interested in games. "People" or "boys" ?? I'd be interested to know your basis for your assertion, and now that the question has been raised I'll start taking informal polls as I go out and give talks. I do about 90 talks a year, and I'll see what the feedback is. And in what aspect of games? Being interested in playing various games is not the same as caring how they work, or caring about the idea that math is used in them. I'm not saying that games can't or shouldn't be used as motivation, but I have grave doubts as to the ubiquity of the appeal that people here seem to be taking for granted. To some extent it's the extremity of the view to which I'm objecting. chaosmachine earlier said: > All math classes should incorporate game programming I really can't believe that such an extreme view is a good thing. It would be akin to saying: Actually math isn't interesting in its own right, we really just need it to write really cool games. Leaving aside that particular comment, I still think that tying math only to applications is a bad thing. Motivation is essential, yes, but sometimes there's math that arises from the math, and only finds application much later, if ever. In short, my personal feeling is that you're wrong that the vast majority of kids would be motivated by games, but I have no stats to back that up, just 25 years of giving talks to school kids. Majority, maybe. Substantial proportion, probably. Far better to get the motivation by using math in a wide, wide range of applications. It's motivation at all, and the sheer breadth that really matters.
- deleted 17y ago
  [deleted]
- Skriticos 17y ago
  I agree. The most effective method would probably be to select various topics of practical usage for maths. That way the likelihood of finding interesting topics for all at one point or the other would increase very much. This would also help the kids to get a little more perspective of how the world actually works, which might benefit them.

ahlatimer 17y ago

I used their videos on youtube while taking a linear algebra course last semester when I needed an extra lesson on a particular topic. I highly recommend them. Everything I saw was presented in a clear, well articulated matter that made it much, much easier to understand than just reading something out of a book.

SandB0x 17y ago
His videos. They were all created by one guy.
Tim_M 17y ago
I have not tried his videos yet but I would highly recommend http://www.youtube.com/user/patrickJMT#g/u http://www.youtube.com/user/patrickJMT#g/u also.

ivan_ah 17y ago

Salman Khan is an extremely talented teacher. I would go as far as to say he is Feynmanesque in his ease with the subjects and ability to come up with good examples for abstract concepts.

edw519 17y ago

With just a computer and a pen-tablet-mouse, one can educate the world! I'll say. Someone's been very busy. Thank you, Khan. This appears to be an excellent resource. The 10 to 15 minute "bite-sized" pieces make it easy to check something out in your spare time. Most definitely bookmarked. I also like how he has added a lot of business/finance stuff, which should probably interest a lot of people here. Looks like a slight change of plans today - I have to check more of this out. [EDIT: I watched several videos in the Venture Capital and Capital Markets section. Definitely worth my while. This teacher appears to be able to make any topic, regardless of complexity, easy to understand. He even has a "happy cursor", which reminds me of football quarterback Peyton Manning's feet when he's getting ready to throw a pass. Funny how you can tell when an expert is in the zone. I'm going to put together a schedule to watch a whole bunch of these videos.]

coffeemug 17y ago

I found that the best way for me to internalize a particular subject in hard science is to follow its history by reading the original papers. It's a hard way to do it, but it helps you understand the motivation, the progression of ideas, and the rigor that went into it. Anything else doesn't quite work for me - I feel like I "sort of" understand, but five minutes after I close the textbook (or the YouTube video) the understanding goes away with it. I watched some of these lectures - they're excellent, but a bit too hand-wavy. Without getting through the rigor there's no hope to gain a complete understanding of the subject matter that stays with you forever.

plinkplonk 17y ago
"I found that the best way for me to internalize a particular subject in hard science is to follow its history by reading the original papers." I've often wondered why math programs (and books) aren't structured this way, explaining the historical context, reproducing the original papers (or explaining the arguments or proofs in the paper if the original happened to be in Latin or whatever), with a section on how the paper helped move the field forward and so on. It doesn't necessarily have to sacrifice rigor to do this, and a s amatter of fact I suspect a "walk the path (taken by the innovators)" approach coupled with strict rigor would make for some awesome books (and get more people interested).
- RiderOfGiraffes 17y ago
  Frequently the historically motivated path is too long or creates too much baggage. It's not always the case, granted, and sometimes the historical development does give you the motivation, but you're still asking for a gifted teacher, and that's rare. A gifted teacher can teach with or without the historical perspective, and in my experience a clean, direct presentation with appropriate motivation and context is usually better. Again, not everything works for everyone.
  - plinkplonk 17y ago
    "but you're still asking for a gifted teacher, and that's rare." Fair enough. Maybe a gifted teacher can write a book :-) "Again, not everything works for everyone." I agree. There are a lot of texts which ignore the history. It would be great to have a few which retraced the paths.

billswift 17y ago

Buying good textbooks to learn from is a lot more cost effective than spending on the high-speed internet connections that is needed to download even a short video in any reasonable time. This "resource" is only useful to already have high-speed internet access.

chaosmachine 17y ago
A month of high speed internet is cheaper than a single text book in many countries. Considering there's probably 40 textbooks worth of material on this one page alone, nevermind the rest of the internet, I'd say priorities should be on providing internet access.
- argv_empty 17y ago
  That and high-speed internet may be a sunk cost anyway.
- pbhjpbhj 17y ago
  OLPC + Khan Academny videos = win.
  - GFischer 17y ago
    Only if they were in Spanish - here in Uruguay we have the OLPC deployed for all schoolchildren, but most students don't have the level of English required :)
    - pbhjpbhj 17y ago
      Well your Spanish is good ...?! It's not a huge stretch to imagine someone sitting and redubbing one of these though is it?
      - GFischer 17y ago
        Well, it sounds like a long project to me :) . It would be a nice project, though, maybe I'll propose it (and contribute to it). Guess the first step would be contacting Khan. PD: Spanish is my mother tongue.

scrrr 17y ago

Excellent website, I'm impressed.

pixcavator 17y ago

I like the style and I appreciate the idea. In fact, I’ve been working on something in the same direction. So, here are a couple of things that I prefer to do differently. First, these are video lectures but without actual students present. As a result, he is essentially talking to himself. I noticed that this causes him to skip some details that students might be wondering about. I prefer to start with actual lectures and initially put them on the web as pdfs (http://users.marshall.edu/~saveliev/Teaching/Fall09/m430/updates.html http://users.marshall.edu/~saveliev/Teaching/Fall09/m430/upd...). Then I transcribe them to an online version (http://inperc.com/wiki/index.php?title=Introductory_algebraic_topology:_course http://inperc.com/wiki/index.php?title=Introductory_algebrai...). This is the second problem I have with his approach. Video just isn’t enough. I don’t’ have to explain to you what video doesn’t have and html does: searchability, cross-linking, speed of download, the ability to read and work at your own pace, etc. Certainly, my way is much slower.

pyre 17y ago
One thing that video has that HTML doesn't: single-file archive ability. Sure you can have a single HTML file as long as you keep it text-only, but most of these topics are going to be diagram (and math figure) heavy. There's just no good way to archive the content for later perusal. (Granted YouTube doesn't want you to directly download the videos, but it's not like it's that hard to circumvent -- and once you have the video you can easily find a player for it on any platform) [Note: I don't count .webarchive or .mht files as 'good enough'. .webarchive files are Safari-only, and I don't even know of a tool to be able to extract data from them. .mht files are 'sorta' supported (IE, Opera, Firefox w/ an extension), but I don't like the idea that the data is Base64/MIME-encoded. Personally I like .maff (Mozilla Archive File Format). It's only supported in Firefox with an extension (and nowhere else unfortunately), but it's basically a Zip file with the HTML/CSS/images inside of it.]
- pixcavator 17y ago
  Well, the site runs on MediaWiki, so you can save the printable version of each article. Even if you print the whole thing, the end result wouldn't be that much different from a bunch of video files for each 15-min lecture.

NyxWulf 17y ago

For most people, they come out of high school not just poor at math, they come out "Math Broken" as one of my friends puts it. The second you mention anything to do with Math, their eyes glaze over and their brain completely disengages. I think there are a lot of things that contribute to that, but generally Math is not taught in a very approachable way. The KhanAcademy is I think a very good start in solving that problem. I came across this site through an article that was on HN sometime last year, around November or December IIRC. Since then I've watched roughly 100 videos on that site. Some of the Finance videos, Trig, and Pre-algebra as a refresher, and I'm now roughly 60 videos into the Linear Algebra videos. Even though I'm in the midst of my master's program now, I've set a goal to watch 2 video's every day as time permits. I am so impressed with this site, and with Salman Khan. The math is very well done, but it's also very approachable. Most of the videos are roughly 10-15 minutes in length and are highly topical. That makes it easy to jump in and pick up a refresher on something you haven't seen for a while. It's also great for getting into something you haven't ever seen before. Personally I haven't ever had Linear Algebra before, and if you've looked at many of the textbooks, they are pretty dense, particularly if you are self learning. I've found this site to be a great resource in getting oriented and it has really helped me get some traction. I have recommended this site to dozens of people, and while most of them don't share my love of mathematics, they have been able to get some traction in various problems by using this site as a supplement. Anyway, as a daily user of the KhanAcademy, I can't say enough good things about the site. I don't think it's a stretch to say it has the potential to revolutionize how math is taught. The one downside to the site I've noticed is the lack of problems sets. There is a tester that will walk you up through the different topics, but unlike the video's you can't just start where you feel you need to, you have to work up through the early material, and that's fairly time consuming. I have a number of other resource's I'm using for problem sets, but it would be nice to have a few problems to work through for each video. Overall an absolutely fantastic resource. Rating: 10/10

RiderOfGiraffes 17y ago
I agree with everyone else that it's a fantastic resource and the material is brilliantly presented, but I don't think it will help with the "Math Broken." I'm absolutely not knocking the resource or the site, I can't say enough good things about it, but if someone is already glazed over at the very mention of math, I don't think the videos here will help. If you think otherwise then I'd really appreciate a suggestion, as I have someone I'd like to point at it ...

sscheper 17y ago

Wow, that's some deep material. Thanks for the link, Chaos.

rick_2047 17y ago

This thing really could have helped me prepare for chemistry for exams in school. I matches my curriculum to the mark. definitely going to share with my juniors.

3dFlatLander 17y ago

I'd like to add a very personal comment to this discussion. I have very bad vision. So much so that in school, I couldn't see the board even when sitting as close as possible. As a result, I'd end up creating notes from a synthesis of what the teacher was saying and what I read in the book as the lesson was going on. This usually didn't work out, and my math skills suffered. This website helped me fill in the gaps of knowledge I had. Actually being able to see the problem being done while given instructions was a great help.

jasonlbaptiste 17y ago

I make this comment every month: There needs to be a comprehensive site that aggregates all the educational videos on the net (lectures, conference talks, screen casts, simple instruction,etc.).

hexis 17y ago
For better or worse, that site is google.com
- jasonlbaptiste 17y ago
  It's a start, but there needs to be 1000x better organization and curation.
mmelin 17y ago
I think that http://academicearth.org/ http://academicearth.org/ does a good job, although they only aggregate courses from universities.
lunchbox 17y ago
Try http://nalandau.com/ http://nalandau.com/
NalandaU 17y ago
We took an initial stab at this and aggregated about 10K videos, and give tools to take notes and tests. Eventually we plan to extensively integrate text contents from Wikipedia, OpenCourseWare etc along with these videos. We are a very young website and would love to get feedback on what are the other resources you guys looking for: http://www.nalandau.com/course/8/programming-(10) http://www.nalandau.com/course/8/programming-(10) regards, Balaji Viswanathan, Founder, NalandaU.com

Slashed 17y ago

My math skills were always bad. I mean, even though I had one of the best scores in school, I could never explain why it works, e.g. why 9^1/2 is the same as sqr(9). Since I want to self-study the Quant Finance, I decided to refresh and develop my math skills up to the Calculus. This website is amazing! Not only it's a good refresher, it's the best source of knowledge created by one man.

eru 17y ago
Interesting. I usually learn best by explaining / teaching.

morphir 17y ago

I feel the need to point out that when I submitted a link to khan academy, no one up-voted it. Why is this? ref. http://news.ycombinator.com/item?id=911882 http://news.ycombinator.com/item?id=911882

onoj 17y ago
I did not see it that time? May also be the title given to the post. Humans are fickle. ( will up vote you now ;)
teeja 17y ago
I'm guessing it was the word 'youtube' combined with 'educate'. (Youtube doesn't have much, uh, 'patina' for some of us.)

rubyrescue 17y ago

How sad that people pay up to 40k to the University of Phoenixes out there, or, worse, take on 40k of unforgivable and practically un-repayable federal student loan debt, when this type of material is available for free!

oPerrin 17y ago

Unfortunately decimals seem to be harder for computers than people :) http://screencast.com/t/ZjUwOWRl http://screencast.com/t/ZjUwOWRl