One of my favorite uses for the supercomputer I carry in my pocket is to tell me when high or low tide will be, and how high or low. I live near the ocean, so tide level is important for beach walks. My goto tide app is TideTrac, $3 on iOS. — KK

V for Wikipedia recreates the childhood joy of getting lost in my old Encyclopedia set. One subject would inspire me to look up another and I’d end up flipping back and forth between pages and indexes for hours. Now I can use my iPhone and seamlessly jump to the next subject with a quick tap. Honestly, this app is so easy and enjoyable to use — totally worth the $4.99. — CD

I signed up for a free 30-day trial of Skillshare because I wanted to improve my drawing skills, and I did. There’s more than 16,000 video classes to choose from. A monthly subscription is $15 per month, but I opted to cancel before the trial ended — they make it really easy and in fact, when I went to cancel they extended my trial another month! They also offer classes in photography, film, cooking and writing. — CD

I used the iNaturalist app when I was hiking and took a picture of a tree that I wanted to know the name of. I just uploaded the picture and labeled it as “I don’t know what this is.” The next morning, I was happily surprised to see an email alerting me that another user identified it for me! It’s like a collaborative classroom on your phone. — CD

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

I’m always amazed and slightly annoyed when the hotel hair dryer works better than my more expensive one back home. This hair dryer is inexpensive, portable and works just as good as any $50+ dryer. — CD

Because of the Tangle Teezer, I actually like brushing my hair after I shower. Just a few, quick strokes and my hair is super smooth and detangled. I’ve used the Tangle Teezer on my 10-year-old niece, who has really long hair and hates getting it brushed, and there was not one complaint. A tip for brushing long hair painlessly: gather all hair in a fist and brush in sections from the bottom up. — CD

Over the years I’ve spent anywhere from $20 to $150 on heat styling tools, and this $25 Remington Curling Wand is the best hair curler I’ve ever owned. It heats up in 30 seconds and the curls keep all day, even through the next day. I owned the smaller ½-inch wand for 5 years before I bought the larger 1-inch wand and now I can curl all my hair in less than 5 minutes. — CD