Minimum Information Principle: Small Cards, Big Recall

You know the card. The front says Explain the Treaty of Versailles. The back is a paragraph. Every time it comes up you mumble half of it, flip, and mark it correct because you got the gist. A week later you still cannot name a single term of the treaty. The fix has a name: the minimum information principle. It is the most useful rule in flashcard writing, and once you see it, you will start splitting cards everywhere.

Wozniak listed it as rule four in his essay Twenty rules of formulating knowledge, first published in 1999 and still the most cited guide to writing flashcards. He is careful to add that simple does not mean short. You are not trying to cut characters. You are trying to make each question so clear that there is exactly one thing to recall.

Think about how a review works. You see a question, try to recall, then grade yourself. With a big card the grade is a guess. Did you pass if you remembered four of five causes? Most people say yes, and the forgotten fifth cause never gets extra practice. With five separate cards, the one you missed comes back tomorrow while the other four wait a month.

There is also a limit on how much you can juggle at once. Psychologist Nelson Cowan reviewed the evidence on short-term memory and argued that people can hold about four chunks at a time, not the seven often quoted. A card that asks you to produce five unrelated facts in one go pushes right against that limit. A card that asks for one fact does not. If you want to work with that limit rather than against it, see the chunking memory technique.

Take the Versailles card from the opening. The back might say the treaty was signed in 1919, made Germany accept blame for the war, limited the German army to 100,000 soldiers, and required reparations. That is four facts. Here is how to split it:

1. In what year was the Treaty of Versailles signed? 1919
2. Which clause of the Treaty of Versailles made Germany accept responsibility for the war? The war guilt clause (Article 231)
3. The Treaty of Versailles limited the German army to how many soldiers? 100,000
4. Under the Treaty of Versailles, what payments did Germany have to make to the Allies? Reparations

Each new card names the treaty in the question. That small piece of context stops cards from blurring together when they come up weeks apart. You can keep one extra card that asks Why did many Germans resent the Treaty of Versailles? for the big picture, but now it sits on top of solid facts instead of replacing them.

Lists are where most fat cards come from. Name the phases of mitosis asks for four things in a set order. Instead, write overlapping cloze cards, each hiding one item while showing its neighbors:

A second card hides anaphase and shows metaphase and telophase on either side, and so on down the list. Each card is tiny, yet together they rebuild the full sequence. The format is covered in more depth in cloze deletion flashcards. For unordered sets, like the bones of the forearm, ask about each member through its own clue: Which forearm bone sits on the thumb side?

Wozniak's first two rules come before this one for a reason: do not learn what you do not understand, and learn before you memorize. If you split a concept you have not grasped, you get a pile of disconnected trivia. Read, explain the idea in your own words, then cut it into cards. He also notes that redundancy is fine. Asking the same fact from two directions, or adding a why card next to a what card, does not break the rule.

• The back has a list, a paragraph or a semicolon.
• You find yourself saying close enough before you flip.
• You remember the shape of the answer but not the content.
• The same card keeps failing for different reasons each time.

The minimum information principle matters even more when cards are generated for you. AI tools often produce long answers because they summarize well. When you generate a set with a tool such as LearnKit, read each card once and split any that ask for two things. You can find more pitfalls in common flashcard mistakes and in our review of AI flashcard generators.

Splitting cards feels like extra work at first, because you end up with more of them. In practice the deck becomes faster, since each card takes seconds, and the facts actually stay. For the full set of card-writing rules, start with how to make effective flashcards.