How to turn a YouTube video into flashcards you actually remember

A video feels easy. The explanation is clear, the pace is good, and you feel you understand everything. The trap is that your attention slips without you noticing. Risko and colleagues measured mind wandering during a recorded lecture that lasted an hour. It grew with time on task, memory for the lecture dropped, and the more people wandered, the less they retained (Risko et al., 2012).

Szpunar, Khan and Schacter tested a remedy on online lectures. Students who answered short tests between the parts wandered less, took more notes and learned more (Szpunar et al., 2013). Keep the idea. A video is worked in slices, with questions in between, not in one block from the first minute to the last.

Step one, pick a video that fits your syllabus and check how long it is. Step two, cut it into slices of ten to fifteen minutes and pause at the end of each. Step three, without looking at anything, write or say what you remember, then go back to the video to see what was missing. Step four, turn each idea into a question and its answer, one idea per card, rather than copying a sentence.

Step five, come back to your cards on dates that get further apart, as explained in Spaced repetition, how long to wait between two reviews, answering from memory before you look at the answer. Check figures, dates and names against your course or textbook, because a video can be wrong or move fast. The pages How to make flashcards that actually work and Active recall, why quizzing yourself beats rereading show how to write good questions and why they work.

Many tools offer to summarise a YouTube video in a few lines, and that is a good way to find out whether it is worth watching. But reading a summary is not the same as working on it. In the review by Dunlosky and colleagues, summarising is rated low utility, while practice testing earns a high rating (Dunlosky et al., 2013).

A summary you reread therefore acts like rereading. It reassures you and it fades fast. What changes the result is turning that summary into questions you answer from memory. The items you hesitate on come back more often, the ones you know wait longer. If a tool hands you a text and nothing else, do that step yourself, or pick a tool that asks the questions for you.

In Lumi, you paste the link of a public YouTube video, or of a web page, and Lumi turns it into cards. The video is read over 60 minutes at most. You then find these cards like the ones from a photo, a PDF, a text or an audio recording, and Lumi forgets them over time before quizzing you again at the right moment, without you setting any dates.

The free plan gives 3 readings a week, and a link counts as one, like a photo, a PDF, a text or an audio recording. If you like, Lumi also reads the questions aloud, a setting you switch on. As with any source, check the cards against your course before you rely on them. The app is not on the App Store yet, and this guide describes what it does at launch.

Knowt, Gizmo and Coconote also start from a source to produce something to study. The table below only repeats what each home page says, read on 7 November 2026. Limits, prices and the quality of the cards are not compared, because those pages do not give them, and they change quickly.

What sets Lumi apart is what comes next. You teach the cards to a companion that forgets over time, then quizzes you right before you forget, and the Mist rises over your sky as the exam gets close. If you mostly want a summariser or a game generator, another tool may suit you better. If you want a study rhythm that is already organised, see also The best study apps in 2026, ranked on five criteria.