Content Types

Overview

The content field on every ContentItem is a discriminated union keyed on type. There are 18 types, grouped below by category. Each section shows the shape of the content object you receive.

Math

arithmetic

A numeric computation with operands and an operator.

{
  "type": "arithmetic",
  "operand1": 14,
  "operand2": 8,
  "operator": "+",
  "displayFormat": "horizontal",
  "missingOperand": null
}

• operand1, operand2 — Numbers or fraction objects ({ numerator, denominator, wholeNumber?, display }).
• operand3 — Optional third operand for multi-step problems.
• operator — One of "+", "-", "×" (U+00D7), or "÷" (U+00F7).
• displayFormat — "horizontal" or "vertical" layout suggestion.
• missingOperand — When set to "operand1", "operand2", or "result", indicates a fill-in-the-missing-number problem.

Language

multiple-choice

A stem question with labeled choices and distractor metadata.

{
  "type": "multiple-choice",
  "stem": "Which word is a synonym for 'happy'?",
  "choices": [
    { "text": "Sad", "isDistractor": true, "distractorReason": "Antonym" },
    { "text": "Joyful", "isDistractor": false },
    { "text": "Angry", "isDistractor": true, "distractorReason": "Unrelated emotion" },
    { "text": "Quiet", "isDistractor": true, "distractorReason": "Unrelated adjective" }
  ],
  "correctIndex": 1,
  "explanation": "'Joyful' means feeling great happiness."
}

fill-blank

A sentence template with one or more blanks to fill.

{
  "type": "fill-blank",
  "template": "The cat ___ on the mat.",
  "answer": "sat",
  "acceptableAnswers": ["sat", "sits"],
  "caseSensitive": false
}

true-false

A statement the student evaluates as true or false.

{
  "type": "true-false",
  "statement": "The Earth revolves around the Sun.",
  "isTrue": true,
  "explanation": "The Earth orbits the Sun once approximately every 365.25 days."
}

short-answer

An open-ended question with optional sample answer and scoring keywords.

{
  "type": "short-answer",
  "question": "What is the main idea of the second paragraph?",
  "sampleAnswer": "The paragraph explains how plants use sunlight to make food.",
  "keywords": ["plants", "sunlight", "food", "photosynthesis"]
}

passage-based

A reading passage with associated comprehension questions.

{
  "type": "passage-based",
  "passage": {
    "text": "Once upon a time, a small fox lived near a wide river...",
    "title": "The Fox and the River",
    "genre": "fiction",
    "wordCount": 210,
    "readingLevel": "Lexile 480L",
    "paragraphs": [
      "Once upon a time, a small fox lived near a wide river.",
      "Every morning, the fox watched the fish leap out of the water."
    ]
  },
  "questionCount": 4
}

Note

The comprehension questions for a passage-based item are returned as separate ContentItems in the same response, following the passage item. Use questionCount to know how many to expect.

Puzzle

matching

Pairs of related items with a pre-shuffled right column.

{
  "type": "matching",
  "instructions": "Match each word to its definition.",
  "pairs": [
    { "left": "Habitat", "right": "The natural home of an organism" },
    { "left": "Predator", "right": "An animal that hunts other animals" },
    { "left": "Ecosystem", "right": "A community of living things and their environment" }
  ],
  "shuffledRight": [
    "An animal that hunts other animals",
    "A community of living things and their environment",
    "The natural home of an organism"
  ]
}

ordering

A sequence of items the student must arrange in the correct order.

{
  "type": "ordering",
  "instructions": "Put these fractions in order from least to greatest.",
  "items": ["1/4", "1/2", "3/4"],
  "shuffledItems": ["3/4", "1/4", "1/2"]
}

word-puzzle

A grid-based word puzzle (word search or crossword).

{
  "type": "word-puzzle",
  "puzzleType": "word-search",
  "grid": [
    ["C", "A", "T", "R"],
    ["D", "O", "G", "S"],
    ["F", "I", "S", "H"],
    ["B", "A", "T", "X"]
  ],
  "words": [
    { "word": "CAT", "clue": "A small furry pet" },
    { "word": "DOG", "clue": "A loyal companion" },
    { "word": "FISH", "clue": "Lives in water" },
    { "word": "BAT", "clue": "Flies at night" }
  ],
  "gridSize": { "rows": 4, "cols": 4 }
}

Visual

diagram

A visual element (number line, shape, clock, etc.) with an associated question.

{
  "type": "diagram",
  "diagramKind": "number-line",
  "diagramData": {
    "min": 0,
    "max": 20,
    "marks": [5, 10, 15],
    "arrow": 12
  },
  "question": "What number does the arrow point to?",
  "answer": 12
}

Supported diagramKind values: number-line, shape, coordinate-plane, bar-model, clock, ruler.

picture-counting

An object to count, designed for K-2 students.

{
  "type": "picture-counting",
  "count": 7,
  "objectDescription": "red apples"
}

Tip

The API returns the count and object description. Your renderer is responsible for displaying the appropriate number of images or icons. Use renderHints.visuals.imageRefs when available for asset references.

data-table

A data table with a question that requires reading or interpreting the data.

{
  "type": "data-table",
  "tableTitle": "Favorite Fruits Survey",
  "headers": ["Fruit", "Votes"],
  "rows": [
    ["Apple", "12"],
    ["Banana", "8"],
    ["Orange", "15"],
    ["Grape", "5"]
  ],
  "question": "Which fruit received the most votes?",
  "answer": "Orange"
}

Type-to-Subject Mapping

While any type can theoretically appear for any subject, in practice certain types cluster by subject area:

Subject	Common Types
Math	arithmetic, picture-arithmetic, diagram, data-table, multiple-choice
Reading	passage-based, multiple-choice, short-answer, true-false, phonics-word-list
Vocabulary	multiple-choice, fill-blank, matching, word-bank, category-sorting
Spelling	spelling-activity, fill-blank, word-puzzle, ordering, tracing-activity
Science	multiple-choice, true-false, diagram, short-answer, category-sorting

Subject-Specific

picture-arithmetic

A visual arithmetic problem for K-2 students using countable objects.

{
  "type": "picture-arithmetic",
  "operand1": 3,
  "operand2": 2,
  "operator": "+",
  "objectDescription": "stars",
  "svgContent": "<svg>...</svg>"
}

spelling-activity

A spelling exercise with a target word, clue, and activity type.

{
  "type": "spelling-activity",
  "word": "because",
  "clue": "I stayed home ___ it was raining.",
  "activityType": "fill-in",
  "scrambledLetters": ["a", "b", "c", "e", "e", "s", "u"]
}

word-bank

A categorized word bank for vocabulary and spelling practice.

{
  "type": "word-bank",
  "words": ["happy", "joyful", "sad", "angry"],
  "categories": ["Positive", "Negative"],
  "instructions": "Sort the words into the correct category."
}

category-sorting

Items to sort into labeled categories.

{
  "type": "category-sorting",
  "categories": ["Living", "Non-Living"],
  "items": [
    { "text": "Dog", "category": "Living" },
    { "text": "Rock", "category": "Non-Living" }
  ]
}

phonics-word-list

A list of words for phonics practice, grouped by sound pattern.

{
  "type": "phonics-word-list",
  "pattern": "short-a",
  "words": ["cat", "bat", "hat", "mat"],
  "instructions": "Read each word aloud. Circle the words with the short a sound."
}

tracing-activity

A tracing exercise for early learners (K-1) with SVG trace data.

{
  "type": "tracing-activity",
  "word": "apple",
  "traceSvg": "<svg>...</svg>",
  "letterCount": 5
}

Next Steps

• Content Items — How these types fit into the full ContentItem model.
• Skills & Standards — Browse the curriculum to find skills that produce each type.