Short answer. Cloze deletion is a flashcard format where part of a sentence is blanked out, and you have to retrieve the missing word(s) from memory. The name comes from "closure" in cognitive psychology — the brain's tendency to complete patterns.
Example
Sentence: "The mitochondria is the powerhouse of the cell."
Cloze deletion card:
Front: "The [...] is the powerhouse of the cell."Back: "mitochondria"Why it's useful
Cloze cards keep context in the prompt. Compared to a traditional "What is the powerhouse of the cell?" prompt, the cloze version:
Preserves the **sentence structure**, which is itself a retrieval cueTests recognition **in context** rather than isolated recallScales well to **multiple deletions** in the same sentenceWhen to use cloze
Sentence-based definitions. "Mitochondria is the powerhouse of the cell" works better as cloze than as Q/A.Sequential facts. "The phases of mitosis are prophase, [...], anaphase, telophase" tests the missing piece with context.Multi-deletion cards. "The capital of [...] is [...]" — two deletions from one sentence make efficient cards.When not to use cloze
Truly isolated facts. "What is the chemical symbol for gold?" doesn't gain from cloze format.When context matters less than recognition. Visual material (anatomy diagrams) is better with image occlusion.Concept questions. "Why does X cause Y?" doesn't fit cloze cleanly.Anki — native support, including multi-clozeRemNote — cloze syntax built into note-takingSuperMemo — original cloze implementationAI flashcard generators — most modern tools generate cloze cards from text inputMulti-cloze cards: deletion strategies
Modern flashcard tools let you create multiple deletions in the same sentence, generating multiple separate cards from one input. Three deletion strategies in common use:
Single-deletion: one blank per card. Simplest; lowest cognitive load. Good for isolated facts.Multi-deletion (one per card): one base sentence generates N cards, each with a different word blanked. Efficient encoding; same prompt context tests different items.All-deletion (single card): one card with multiple blanks at once. Hardest; closest to free recall. Use sparingly for items where the full sentence structure is the goal.Cloze deletion vs Q/A: a practical test
For each piece of material, ask: *is the sentence structure itself part of what I want to remember?* If yes (e.g., a chemistry mechanism, a legal rule, a historical sequence) → cloze. If no (an isolated fact like a capital city or a person's birth year) → Q/A. Cloze wastes effort when the sentence structure isn't carrying information.
Cloze pitfalls
Too-obvious blanks. "The capital of [France] is Paris" — the blank position gives the answer away. Either delete "Paris" or rephrase.Multi-cloze across whole paragraphs. Cards with 6+ blanks in a paragraph become reading exercises, not retrieval. Cap at 2-3 blanks per card.Cloze cards on material you don't yet understand. Cloze tests retention; it can't replace the initial encoding step. Read the source first, then make cloze cards from it.[Spaced Repetition Flashcards — Student Guide](/blog/spaced-repetition-flashcards-student-guide)[What Is Active Recall?](/blog/what-is-active-recall)[Spaced Repetition vs Flashcards](/blog/spaced-repetition-vs-flashcards)[Spaced Repetition Guide](/blog/spaced-repetition-guide)[Leitner System Flashcards](/blog/leitner-system-flashcards)A standard flashcard has two sides: question on the front, answer on the back. The problem: you read the question, recognize what it's asking, flip, and feel like you "knew" it. Recognition isn't recall.
A cloze deletion forces you to fill in a blank inside a sentence — you must produce the missing word from context. The retrieval load is higher, and the contextual sentence supplies cues that aid memory formation.
A practical test of the difference: take 20 vocabulary terms. Half as standard cards, half as cloze sentences. Test recall a week later. Cloze cards consistently produce 20-40% better retention.
Vocabulary in context. "She showed [resilience] in the face of adversity" beats "resilience: the ability to recover."Definitions inside paragraphs. Blank the term, leave the definition; or blank the definition, leave the term.Fact memorization. "The Treaty of [Versailles] ended World War I in [1919]."Sequenced steps. "After [encoding], information moves to [short-term memory] before [long-term consolidation]."Formula recall. "F = m × [a]" with the acceleration term blanked.When NOT to use cloze deletion
Procedural skills. You can't cloze a coding pattern or surgical procedure into existence. Use practice problems instead.Conceptual understanding. A cloze can test recall of a concept's name, but not whether you understand the concept. Use Feynman-style explanations alongside.Multi-step problems. Cloze deletes a single token; multi-step problems need a different format.Highly visual content. Cloze works on language. For images, diagrams, or spatial relationships, use image occlusion instead.Building good cloze cards
A few rules that distinguish strong cloze cards from weak ones:
Blank one thing per card. Multiple blanks confuse retrieval cues and often turn into "complete the sentence" puzzles, which are harder to grade and to space.Pick the highest-information word. A sentence has many possible blanks; choose the one that carries the conceptual weight, not a filler word.Provide enough context. A 4-word sentence is rarely enough. Aim for 10-25 words that situate the blank.Avoid synonyms that would also be correct. "The author was [happy/glad/pleased]" creates ambiguity. Either narrow the wording or accept multiple valid answers.Source from real material. Quotations from textbooks, articles, or your own notes produce more memorable cards than synthetic sentences.Cloze deletion in spaced repetition systems
Anki, RemNote, Mochi, and SuperMemo all support cloze cards natively. Workflow:
Highlight the term you want to blank.The app generates the card with that term hidden.Schedule per FSRS / SM-2 — same intervals as standard cards.On review, type or mentally produce the missing term before flipping.Grade your recall (easy / hard / again); the algorithm adjusts the next interval.Most experienced SRS users have a mix of formats — cloze for definitions and vocabulary, image occlusion for anatomy and diagrams, standard cards for relational concepts.
Common implementation mistakes
Cloze-fying everything. Not all material benefits. Tables, equations, and lists often work better in other formats.Skipping the context. A cloze stripped of context becomes a regular flashcard, just slower to read.Same sentence, multiple cards with different blanks. Reinforces the surface pattern of the sentence rather than the concept. Vary the sentence between cards.Cloze cards that test trivia rather than understanding. Years and percentages cloze easily but rarely matter. Cloze the concepts, not the decoration.Generate cloze-style flashcards from your notes.
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