The Squeeze Theorem explained by Sal Kahn, the creator of the online learning resource, Kahn Academy. Credit: Kahn Academy.
Here’s a gem of a website that I wish I had known about a long time ago.
It’s the Khan Academy, which is a library of 2700 videos on a wide range of topics spanning mathematics, physics, economics, art history, government, banking, test prep and more.
Its mission is simple, and it’s free! From the website,
The Khan Academy is an organization on a mission. We’re a not-for-profit with the goal of changing education for the better by providing a free world-class education to anyone anywhere.
All of the site’s resources are available to anyone. It doesn’t matter if you are a student, teacher, home-schooler, principal, adult returning to the classroom after 20 years, or a friendly alien just trying to get a leg up in earthly biology. The Khan Academy’s materials and resources are available to you completely free of charge.
The brainchild of Sal Kahn, Khan Acacemy videos are about 10 minutes long and are optimized for computer viewing. Most of the videos are done by Kahn himself, but he pulls in experts to handle lessons beyond his reach, like art history. The website is fresh, personal, easy to navigate and useful. For example, it leaves a dot next to each video to mark the ones that have been viewed, either partially or completely.
Khan’s background is in math, computer science and investment management and that comes through with the mix of videos skewed heavily to mathematics: arithmetic, algebra, geometry, calculus and statistics. Based on a quick glance through the offerings, it looks like about two-thirds are math-oriented. There are also quite a few videos that explain banking and finance, topics that usually are given only a cursory treatment in high school.
Also, there are a lot of videos on test prep for AP math exams, California Standards Test, SAT, GMAT and more.
Khan does not follow a set curriculum. Instead, as he says on the website, “I teach the way I wish I was taught. The lectures are coming from me, an actual human being who is fascinated by the world around him.”
I watched the video “Squeeze Theorem” in the calculus section, mostly because I don’t remember learning about anything with such a memorable name. Khan introduces the theorem with a non-mathematical example, then follows up with the math, so the understanding of the concept preceeds the formalization of the principle. The “aha moment” comes when he loops around and connects the math to the non-math example.
Because the videos are so granular, they are also a terrific resource for professionals needing to brush the rust off of things learned in school.