> ## Documentation Index
> Fetch the complete documentation index at: https://docs.learningcommons.org/llms.txt
> Use this file to discover all available pages before exploring further.

# Background Knowledge Demands

> Measure how much prior knowledge a reading passage assumes, listing key concepts and whether students at a grade level have likely encountered them.

[Evaluator last updated August 27, 2026.](#evaluator-release-history)

<EarlyAccess isBreaking={false} />

## Overview

The Background Knowledge Demands evaluator assesses the background knowledge complexity of reading passages:

* Evaluates how much prior knowledge a text relies on
* Lists key concepts in the text
* Evaluates whether students have likely encountered these concepts before

## At a glance

|                      |                                                                                                                                                                                                                                                                       |
| :------------------- | :-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Supported grades** | 3–12                                                                                                                                                                                                                                                                  |
| **Rubric**           | [Student Achievement Partners (SAP)](https://learnwithsap.org/) ↗'s [Qualitative Text Complexity Rubric for Informational Text](https://learnwithsap.b-cdn.net/app/uploads/2026/04/Qualitative-Text-Complexity-Rubric-Informational.pdf) ↗ (Subject Matter Knowledge) |
| **Model used**       | Gemini 3 Flash preview (`gemini-3-flash-preview`) with temperature of 0 <Note>The evaluator was built and validated using this specific model and temperature. Other configurations will produce different results and may have lower accuracy.</Note>                |

## Getting started

Follow the [Quickstart](/evaluators/getting-started/quickstart) to start using this evaluator:

| Access method             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
| :------------------------ | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| **Evaluators playground** | [View in Platform](https://platform.learningcommons.org/apps/evaluators/playground) ↗                                                                                                                                                                                                                                                                                                                                                                                                                         |
| **SDK**                   | [TypeScript](https://github.com/learning-commons-org/evaluators/blob/main/sdks/typescript/src/evaluators/text-complexity/ela-reading/background-knowledge-demands.ts) ↗                                                                                                                                                                                                                                                                                                                                       |
| **Other**                 | [Python notebook](https://github.com/learning-commons-org/evaluators/blob/main/evals/text-complexity/ela-reading/background-knowledge-demands/example_notebook.ipynb) ↗<br /><br />Prompts: [`system.txt`](https://github.com/learning-commons-org/evaluators/blob/main/evals/text-complexity/ela-reading/background-knowledge-demands/system.txt) ↗ and [`user.txt`](https://github.com/learning-commons-org/evaluators/blob/main/evals/text-complexity/ela-reading/background-knowledge-demands/user.txt) ↗ |

## Inputs

| Input           | Description                                                                        | Required |
| :-------------- | :--------------------------------------------------------------------------------- | :------- |
| **Text**        | Informational text to evaluate<br />10 - 10,000 words (\< 1,200 words recommended) | Yes      |
| **Grade level** | Target student grade level                                                         | Yes      |

## Output

| Field                           | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
| :------------------------------ | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Complexity score**            | <ul><li><strong>Slightly complex:</strong> Relies on everyday, practical knowledge; includes simple, concrete ideas</li><li><strong>Moderately complex:</strong> Relies on common practical knowledge and some discipline-specific content knowledge; includes a mix of simple and more complicated, abstract ideas</li><li><strong>Very complex:</strong> Relies on moderate levels of discipline-specific or theoretical knowledge; includes a mix of recognizable ideas and challenging abstract concepts</li><li><strong>Exceedingly complex:</strong> Relies on extensive levels of discipline-specific or theoretical knowledge; includes a range of challenging abstract concepts</li></ul> |
| **Reasoning**                   | Detailed synthesis of why the text fits the chosen complexity level                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
| **Identified topics**           | Core subjects and concepts found in the text                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
| **Curriculum check**            | Whether the topics are standard K-8 knowledge or specialized high-school-level knowledge                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
| **Assumptions and scaffolding** | What the author assumes the reader already knows versus what is explained in the text                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
| **Friction analysis**           | Whether difficulty comes from vocabulary/sentence structure or from actual background knowledge demands                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |

## Interpreting results

| Output                                              | How to use                                                                                                                                                                                                                                                                                                                                                                                                    |
| :-------------------------------------------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| **Complexity rating**                               | <ul><li><strong>Slightly complex:</strong> Confirm text relies on everyday knowledge students likely have</li><li><strong>Moderately complex:</strong> Plan light scaffolding for discipline-specific terms</li><li><strong>Very complex:</strong> Pre-teach key concepts before independent reading</li><li><strong>Exceedingly complex:</strong> Flag texts that assume extensive prior knowledge</li></ul> |
| **Identified topics + Assumptions and scaffolding** | Match text to what students have already encountered<br /><br />**Example**: Use identified topics, curriculum check, and friction analysis to decide what to pre-teach or explain in the text                                                                                                                                                                                                                |

## Evaluator release history

| Date            | Changed              |
| --------------- | -------------------- |
| August 27, 2026 | Minor prompt updates |
| March 13, 2026  | First release        |

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