> ## 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.
# Vocabulary Complexity
> Identify Tier 2, Tier 3, and archaic words in a text and score vocabulary complexity against grade-level background knowledge with this evaluator.
[Evaluator last updated August 27, 2026.](#evaluator-release-history)
## Overview
The Vocabulary Complexity evaluator gives developers fine-grained vocabulary insights that help ensure texts use words that align with grade-level expectations and support growth in academic language:
* Estimates the background knowledge that a student at the target grade level is likely to have
* Identifies complex words in the text ([Tier 2](/evaluators/understanding-evaluators/core-concepts#tier-2), [Tier 3](/evaluators/understanding-evaluators/core-concepts#tier-3), [archaic](/evaluators/understanding-evaluators/core-concepts#archaic), etc.)
* Evaluates overall vocabulary complexity relative to the background knowledge estimate
## At a glance
| | |
| :------------------- | :----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Inputs** | Informational text to evaluate and grade level |
| **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) ↗ |
The evaluator was built and validated using the model and temperature below (other configurations will produce different results and may have lower accuracy):
| | |
| :-------------- | :---------------------------------------------------------------------------------- |
| **Model used** | GPT-4o (Step 1); Gemini-2.5-pro (Step 2, Grades 3–4); GPT-4.1 (Step 2, Grades 5–12) |
| **Temperature** | 0 |
## 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** | [Python](https://github.com/learning-commons-org/evaluators/blob/main/sdks/python/src/learning_commons_evaluators/evaluators/vocabulary.py) ↗ and [TypeScript](https://github.com/learning-commons-org/evaluators/blob/main/sdks/typescript/src/evaluators/vocabulary.ts) ↗ |
| **GitHub** | [Python notebook](https://github.com/learning-commons-org/evaluators/blob/main/evals/student-facing-text/ela-reading/vocabulary-complexity/example_notebook.ipynb) ↗
Prompts ([`system.txt`](https://github.com/learning-commons-org/evaluators/blob/main/evals/student-facing-text/ela-reading/vocabulary-complexity/system.txt) ↗ and [`user.txt`](https://github.com/learning-commons-org/evaluators/blob/main/evals/student-facing-text/ela-reading/vocabulary-complexity/user.txt) ↗) |
## Inputs
| Input | Description | Required |
| :-------------- | :---------------------------------------------------------------- | :------- |
| **Text** | Informational text to evaluate
Optimal length: 130-205 words | Yes |
| **Grade level** | Target student grade level | Yes |
## Output
| Field | Description |
| :---------------------- | :-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Tier 2 words** | [Tier 2](/evaluators/understanding-evaluators/core-concepts#tier-2) words in the text — words commonly used in academic settings, more complex than colloquial or everyday language, often with multiple meanings |
| **Tier 3 words** | [Tier 3](/evaluators/understanding-evaluators/core-concepts#tier-3) words in the text — overly academic or domain-specific words |
| **Archaic words** | [Archaic](/evaluators/understanding-evaluators/core-concepts#archaic) words in the text — common words used in an archaic way, not commonly used in modern conversational language |
| **Other complex words** | All other words that can increase complexity of the text (e.g., idioms, unfamiliar proper nouns that function as vocabulary) |
| **Complexity score** | - Slightly complex: Uses everyday, familiar vocabulary with few academic or domain-specific terms.
- Almost entirely contemporary and conversational
- Very low proportion of complex words (archaic, subject-specific, academic)
- Easy to understand and does not impede comprehension of the bulk of the text (1-2 quick pauses for processing by the student may occur)
- Moderately complex: Includes a mix of familiar and academic vocabulary, with some Tier 2 or Tier 3 terms that may require support.
- Mostly contemporary and conversational
- Low proportion of complex words (archaic, subject-specific, academic)
- Generally allows students to comprehend the bulk of the text with little difficulty, though there may be occasional pauses for clarification (several quick pauses or occasional prolonged pauses may occur)
- Very complex: Relies heavily on Tier 2 and Tier 3 vocabulary with limited contextual scaffolding.
- Often unfamiliar, archaic, subject-specific, and/or overly academic
- Often presents challenges that may slow down comprehension, but does not completely block the comprehension of the bulk of the text
- Exceedingly complex: Uses dense academic and domain-specific vocabulary that is likely to be inaccessible without significant support.
- Mostly unfamiliar, archaic, subject-specific, and/or overly academic
- May be ambiguous or purposefully misleading.
- Makes comprehension of the bulk of the text very challenging and requires careful effort to interpret
|
| **Reasoning** | Detailed explanation of the rating. Grades 3-4 reference density and cumulative effect, contextual scaffolding, abstract vs. concrete vocabulary, conceptual load, and the provided student background knowledge; other grades reference the annotation guide and rubric |
## Evaluator release history
| Date | Changed |
| ------------------ | -------------------- |
| August 27, 2026 | Minor prompt updates |
| September 23, 2025 | First release |
## Related topics
Explore other evaluators that assess qualitative text complexity.
Explore the expert-annotated benchmark behind literacy evaluators.
Run an evaluator in the Evaluators playground, a Python notebook, or with
the SDK.