Cloze Deletion: Fill-in-the-Blank Cards Done Right

Cloze deletion is the simplest way to turn a sentence from your notes into a flashcard: you hide one part and try to fill it in. The mitochondria produce most of the cell's ___ through aerobic respiration. You answer ATP, flip, and check. It takes seconds to make, keeps the fact inside its context, and works for almost any subject.

It is also easy to misuse. Hide the wrong word and you are testing grammar. Hide too much and the card becomes a guessing game. This guide shows how to write cloze cards that test what matters, with examples and the syntax used by Anki.

The Anki manual uses a neat example. Start from Canberra was founded in 1913. Hide the year and you get one card: Canberra was founded in [...]. Hide the city and you get a second card from the same sentence: [...] was founded in 1913. Both cards come from one note, so if you fix a typo, both update.

SuperMemo's twenty rules of formulating knowledge call cloze deletion easy and effective, and recommend it especially to beginners who struggle to keep cards small. A sentence with one blank naturally follows the minimum information principle.

The risk with cloze is that the sentence itself carries hints. If you have seen the same sentence twenty times, you may recognize its shape and fill the gap without knowing the fact. That is why a healthy deck mixes both formats. Our pillar guide on how to make flashcards covers the other card types.

Take this note: In the kidney, antidiuretic hormone increases water reabsorption in the collecting duct. There are three useful blanks: the hormone, what it increases, and where. There are also bad blanks, such as the or in. Each useful blank becomes its own card.

Here is the trap. Every blank you add as a separate card is another card in your daily reviews. The Anki manual estimates that 20 new cards a day leads to roughly 200 reviews a day. A dense paragraph with eight clozes is eight cards, not one. Choose the two or three blanks an exam would really ask for, and see how many flashcards per day you can sustain.

The ___ regulates blood sugar could be insulin, glucagon or the pancreas. Adding [hormone, lowers] makes the card fair. Keep hints to a category or a direction. If the hint contains the first letters of the answer, you are back to recognition.

Lists are where cloze cards most often go wrong. Say you need the four stages of mitosis in order: prophase, metaphase, anaphase, telophase. One card that hides all four is hard to grade and easy to half-know forever. Instead, write the sentence once and make four cards, each hiding one stage:

1. The stages of mitosis are ___, metaphase, anaphase and telophase.
2. The stages of mitosis are prophase, ___, anaphase and telophase.
3. The stages of mitosis are prophase, metaphase, ___ and telophase.
4. The stages of mitosis are prophase, metaphase, anaphase and ___.

Each card tests one position with the rest as support. Once these are easy, add a single question card that asks for the whole list in order with no context. That final card checks that you can produce the sequence on your own, which is what a written exam will need. For lists longer than about seven items, split them into groups first.

A five-minute routine for turning notes into cloze cards

This works well right after a lecture. For a full system, see turning lecture notes into flashcards. For language learning, cloze sentences are one of the best ways to learn words in context; vocabulary flashcards shows how.

Cloze cards shine when they are short and pointed. Use them for the facts that sit naturally in a sentence, pair them with why questions for everything else, and keep an eye on how many cards each paragraph creates. The goal of active recall is to produce answers, and a good blank makes you do exactly that.