This four-step method for learning difficult subjects was developed by physicist Richard Feynman when he was a student at Princeton University. All the steps are important, but the most important step is the one where you have to teach what you’ve learned in a simple way so a new student can understand it. If you can’t do that, you don’t really understand it yourself. — MF

I love good explainer videos. The best are made by Kurzgesagt. Their 5-minute videos are stunningly animated and cover topics such as automation, genetic engineering, gamma ray bursts, and ebola. They often leave me in awe about our universe. — MF

My favorite example of how video is displacing much of what books used to do is this short YouTube video on the History of Japan. In only 9 minutes it covers the complex, twisted, obscure history of Japan but with insight and clarity. (One of its subtle tricks is to use nick names instead of proper names for people.) The clip has racked up 30 million views because it teaches so well. — KK

Sideways Dictionary uses analogies to explain technology. You can contribute your own, upvote those you like or downvote those you don’t find helpful. Here’s one to describe API: “It’s like a LEGO brick. An application without an API is like a LEGO brick without nodules (are they called nodules?) – it’s not much fun and you can’t build anything new with it.” — by Nick Asbury. — CD

Lynda.com has an excellent collection of training videos for learning programming, design, bitcoin fundamentals, bookkeeping, and much more. Lynda charges a monthly fee, but if you have a library card, the chances are you can become a Lynda member for free. Here’s a link for L.A. residents to use Lynda (and other great stuff, like the digital edition of the New York Times) for free. — MF

A great one-episode podcast that taught me a lot about negotiation that I wished I had learned decades ago: “How Creatives Should Negotiate”, run by Ramit Sethi on the Tim Ferriss podcast. As the title suggests this 1.5-hour seminar is aimed at creatives such as photographers, musicians, designers, and the like, but really the advice is useful to anyone. — KK

Two Slate journalists attended a class on negotiation skills at Columbia Business School and created a 10-episode podcast called Negotiation Academy. After listening to the series, I feel like I can negotiate a better deal for myself from now on. — MF

A reminder of the progress we all enjoy. A curious fellow decides to spend six months growing his own wheat and vegetables, making his own cheese and meat, evaporating his own salt in order to make his own sandwich from scratch. He spent $1500 on this lunch, and in this short, How To Make A $1500 Sandwich, he gives the particulars of what is really involved in our everyday consumption. Like the Toaster Project, which was an earlier attempt by an artist who spent a year to make a $30 electric toaster from scratch (iron ore, petroleum plastic), it conveys in concrete terms the huge subsidy we get from modern civilization. I repeatedly return to these brilliant examples. — KK

Anki is a free flashcard program that uses the Spaced Repetition System (SRS) to present words or facts you have trouble remembering more frequently than ones you can recall easily. I’m using Anki based on the advice in the book Fluent Forever: How to Learn Any Language Fast and Never Forget It, which I highly recommend. — MF

Tiny Cards is a free smartphone app that lets you make spaced repetition flashcards to help you learn languages, history facts, the elements, constellations, or anything else. I’m using it to help me with my Japanese vocabulary. — MF

The website The Kid Should See This gathers the best short videos that explain how the world works. Subjects includes nature, science, technology, art, and politics. So far they have collected 2,600 videos that “are not made for kids, but are perfect for them.” The videos are really great for any do-it-yourselfer, and for any life-long learner. In fact, the site might be called “The Adults Should See This.” — KK

The Learning Toolbox website has a bunch of useful tips for getting the most out of studying. It was created for students with “mild disabilities,” but I think it’s useful for all students and non-students too. As someone who gets distracted easily, I appreciated the tips on how to focus on lectures and while reading. — MF

For high-schoolers: The Khan Academy, the premier free online classroom, will tailor an SAT study course to your personal abilities based on your PSAT scores. They claim to be able to increase scores by 115 points. Sign up at Khan Academy, give PSAT permission to share your completed test, and Khan will create a free course designed for you personally. It will focus on your weak areas. BTW, they found that students who study together learn 2.5x as much as those who study alone. — KK

In the last six months I’ve learned over 500 kanji characters and Japanese vocabulary words using WaniKani, a “spaced repetition system” flashcard website. The first 3 levels are free, after that you can pay by the year or buy a lifetime account. (Disclosure, my wife used to work at WaniKani’s parent company). — MF

Dr. Moku’s Hiragana and Katakana apps use mnemonics to help you memorize the Japanese syllabaries. Within 60 minutes I had all the syllables memorized (roughly 100). — MF