Need to refresh your math skills? From basic algebra to calculus and beyond.
khanacademy.org
khanacademy.org
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
If you think otherwise then I'd really appreciate a suggestion, as I have someone I'd like to point at it ...
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.]
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.
[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.]
Linking to this to the subject matter, most of the lessons have to do with math and science, in a way that requires diagrams and specific notations. Both of which cannot be represented in plain-text or HTML without external files.
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.
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).
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.
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.
(I 'spect part of it is that history is a 'humanity' ... but also that it's because they didn't get the history either, and didn't have time to learn it well enough to teach it.)
The physics department (major US university) actually hired a history of science scholar, and I heard grumbling that he should be paid for by another department.
In my physics class in high school, we discussed the progression of models of the atom. Each time, we learned what experiment led to the new thoughts, and how surprising it was. I thought this was a great way to learn the topic. We didn't, however, spend too much time on the history and never read any of the original papers.
Note: We did have a great teacher.
On the other hand, one difficulty with teaching topics historically is that it is hard to group things by topics. For example, in mathematics, the function is a relatively recent idea. Newton died before the function was thought up, but calculus is usually taught as "take the derivative of a function." This is not to say that history would be useless in this case, but it may require even more talent from the teacher.
http://www.amazon.com/Mathematics-its-History-John-Stillwell...
What we really need is professors knowledgeable enough to answer these questions or point the student to the right texts.
But I care.
In your world do only potato sellers need text books?
I wasn't talking about textbooks for potato sellers, so I fail to see how this is relevant. The implicit audience in my post is a reader of HN. Does your potato vendor post on HN? ;-)
I wasn't talking about elementary mathematics in case that wasn't clear from the context. So now you know.
As you no doubt know already, I was responding to a very specific comment that said "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." and I just made an observation noting my surprise why (some) textbooks aren't structured to help people like the commenter , not your potato vendor whom I haven't had the honor of meeting.
"What we really need is professors knowledgeable enough to answer these questions or point the student to the right texts."
Another strawman?
(a)I was asking for some textbooks to be structured this way for people who like learning that way.
(b) there is no reason not to wish for good professors and textbooks of all kinds (NOT professors ExclusiveOr textbooks - where did you get that idea?) .
Since I wasn't advocating that potato sellers should be taught the history of additions and fractions, or that textbooks should be substitutes for good professors, I'll leave you be to hack at your favorite strawmen in peace ;-).
I watched some of these lectures - they're excellent, but a bit too hand-wavy.
sure, but what more can you expect from 10 minutes? i don't care how great a 10-minute youtube video is, it can never provide the depth that sophisticated primary sources can. but then again, we shouldn't expect it to go nearly that deep :)
..but reading the original papers? I can't imagine ever deciphering Newton or Maxwell (before Heaviside fixed up the equations, it was some horrific mess of like, 20 equations with 20 unknowns). There are great benefits in a clean, logical development.
On the other hand, I hear Dirac's papers were remarkably clear. Maybe reading the originals is easier for math?
"..if one wishes to make progress in mathematics, one should study the masters and not the pupils" -Abel
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.
And yes, who doesn't like games?
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.
> 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.
Just to clarify, that was kind of a joke. At least, it wasn't meant to be taken as an all or nothing extremist demand.
If I was going to rewrite that comment, knowing it would be taken literally, it might read something more like:
All math classes should incorporate fun "real world" applications, beyond just theory. More people would pay attention.
But my point was not if everyone is interested in games and game programming, but rather that you can't please everybody all the time, and game programming can be just one application, which could be enough to show students there are many applications for what they are learning. If you want to teach other applications, that's perfectly fine, as long as you reach your teaching goal.
>"People" or "boys" ??
Depends on the game.
In my experience everyone likes some kind of game. It's the rare person who can't let their hair down at least every once in a while and enjoy some meaningless structured play.
Sure, your wife may not like Super Mario Brothers, but I can almost guarantee that if she took a probability and statistics class or studied combinatorics that coin flipping, dice tossing, dominoes, odds-taking and card playing were major topics of discussion and about the only examples that can be used outside of pure theory that represented a simple enough model of the topic for instructional and study purposes and had as common of a shared experience as possible.
That being said, I never played many card games growing up, and when those topics were discussed I had trouble relating and thought that like your wife it made it hard to relate to. But at least I knew what it was and what the basic concepts were.
Similarly you would be very hard pressed to find anyone younger than about 30 who couldn't relate to some kind of game.
Games may occasionally be mentioned in passing when applicable, such as using traditional games as examples of probability or the importance of linear algebra and trigonometry in video games.
The problem is that the mathematics used in video games aren't introductory. You need to know a lot about these foundations before you can get very far. Chances are, if you are studying them at such a level, you know what role they play.
Ultimately I suspect the only way to succeed in maths early on is to consider it to be a kind of game. That is, puzzle solving for fun.
> How do you motivate basic maths, though?
> Not everything can be directly connected
> to drug couriers and what not.
So far I've always succeeded, and I don't even think I'm especially gifted. On current experience, if you name a topic or technique, even in basic math, I can probably relate it to and motivate it by (comparatively) real world requirements at an appropriate level. > Ultimately I suspect the only way to succeed
> in maths early on is to consider it to be a
> kind of game. That is, puzzle solving for fun.
I agree entirely that people who are going to go and do science or math probably have an element of problem-solving enjoyment, and for them, such motivation not only will work, but is the most appropriate. Getting such people to puzzle over why something happens, and getting them curious about how it works is probably the best thing you can do for them.When I'm talking to people I show them a couple of things and gauge their reactions. Here are two:
http://www.fieggen.com/shoelace/ianknot.htm
http://news.ycombinator.com/item?id=604347
Any given person will react in one of two ways. One is to half-shrug as if to say "who cares?" and then move on, the other is to look closer and say "Do that again." People in the former group are most likely to need motivating with things that matter to them which might (but might not!) include games. The others can just have their curiosity poked and you're off and running.
YMMV, personal opinions only, etc, etc.
I think one exercise I would give my pupils would be to determine the real prices of mobile phones.
Enjoyed the shoelace link, will try it the next time I tie my shoes.
There needs to be a comprehensive site that aggregates all the educational videos on the net (lectures, conference talks, screen casts, simple instruction,etc.).
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)
regards, Balaji Viswanathan, Founder, NalandaU.com
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.
It's not a huge stretch to imagine someone sitting and redubbing one of these though is it?
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.
I was thinking more akin to having a site that would facilitate the redubbing allowing you to upload a dub via the site which would then be patched onto the video. You'd need some verification and voting on best dubs.
Even some subtitles might help, and that's a much smaller project :)