Making Reading Levels Work for Your Readers

If you’ve ever searched for a “just right” text for a struggling reader, you’ve probably checked a readability score. Maybe it was a Lexile level, Dale-Chall score, ATOS level, or Flesch-Kincaid grade level.

These scores can be helpful, but they don’t tell the whole story.

Readability formulas estimate the difficulty of a text, not whether a student will understand it. For older struggling readers, successful reading depends on much more than a number.

What Is Readability?

Readability is an estimate of how difficult a text is likely to be. It predicts how easily a reader may understand a passage based on features of the text itself.

Most readability formulas examine features such as:

• Sentence length
• Number of syllables in words
• Vocabulary difficulty
• Word frequency
• Sometimes sentence structure

The result is a guess at the reading skill a person might need to understand that text.

Because it is an estimate, a prediction, and a guess, consider readability to be a starting point, not the finish line.

Understand the Limitations

Readability is often described as the difficulty of a text. In reality, reading difficulty depends on the interaction between the text and the reader.

Keep these limitations in mind:

1. Most readability formulas focus on sentence length, vocabulary, and word frequency rather than the complexity of the ideas.
2. Readability levels are estimates, many with a wide range of standards of error.
3. Because different readability systems give different scores for the same piece of text, they are difficult to trust.
4. Many formulas analyze only portions of a text rather than the entire work, so scores may not reflect the complete work.
5. Readability scores can be manipulated by shortening sentences or replacing words without actually making the text easier to understand.

Readability Formulas

Proprietary algorithms are used to estimate the level of reading skill someone needs to understand a passage based on features of the text itself.

Measure	Information	Pros	Cons	Standard Error Measurement
Lexile*	One of the most widely used readability systems in schools. Measures: • Word frequency • Sentence length Reported as: BR (Beginning Reader) through 2000L+	• Widely available • Considers entire texts • Easy to match books to students • Helpful for tracking reading growth over time	• Does not account for background knowledge. • Poetry, dialogue, and technical texts can receive misleading scores.	±30L to ±50L Ranges on Lexile charts incorporate this SEM.
Flesch-Kincaid Grade Level	This formula is built into Microsoft Word and many online readability tools. Measures: • Average sentence length • Average syllables per word Reported as: Approximate grade level	• Easy to calculate • Quick estimate of text complexity	• Longer words are not always harder. • Short, unfamiliar technical words may be more difficult than long, familiar words.	No SEM was reported as this is a strictly mathematical formula
ATOS	Used as the basis for many book-leveling systems, including Accelerated Reader. Measures: • Word length • Sentence length • Vocabulary difficulty • Book length Reported as: Grade level	• Considers multiple features of the text.	• Cannot measure knowledge demands or text organization. • Book length does not always reflect reading difficulty.	No SEM was reported as this is a strictly mathematical formula
Dale-Chall Formula	Unlike many readability formulas, Dale-Chall compares words against a list of familiar vocabulary. Measures: • Sentence length • Percentage of unfamiliar words	• Often reflects vocabulary difficulty more accurately than syllable counts alone.	• Familiar word lists may not reflect students from different backgrounds or multilingual learners. • Does not account for sentence complexity or text cohesion, just length.	±0.8 Grade Level
Coh-Matrix	Primarily used by researchers. Measures: • Sentence complexity • Vocabulary • Text cohesion • Referential connections • Narrativity • Syntactic simplicity	• Provides a deeper analysis of why a text is difficult. • Goes beyond simple readability formulas.	• Impractical for everyday classroom use. • Results require interpretation.	No SEM was reported as this is a strictly mathematical formula

*We believe Lexile to be a trustworthy prediction of student comprehension because its results are based not only on a large sample of readers but also on an average of text segments from an entire book.

How to Explain Readability Scores to Students and Parents

Students frequently receive a Lexile or readability score after an assessment, but these scores describe the text, not the student.

Instead of saying, “This is your reading level,” try saying:

This is the level of text you could problem-solve at when you took this assessment.

Here’s why:

• That phrase empowers the student to problem-solve text. It implies there is something that can be controlled by the student.
• It begins a conversation that builds trust and buy-in: Would you like to know more ways to problem-solve text so that it’s easier? I am happy to show you how to solve ______ [long words, difficult sentences, tough passages] so that this number can increase.

Of course, the same language works well with families:

This is the level of text your child could problem-solve at the time of the assessment.

This wording encourages productive conversations about instruction, effort, accommodations, sleep, attention, and other factors that influence reading performance.

Use Readability Scores to Guide Instruction, Not Limit It

Use a readability score as a baseline because they are just a hint of what’s going on with a child.

Then determine what’s in the way of achieving problem-solving of grade-level text.

It could be the student’s

• Decoding, syntax, vocabulary, or fluency skills
• Lack of background knowledge
• Working memory stresses
• Executive functioning weaknesses
• Motivation and reading stamina

Teach or address that part.

Next, increase text levels from where they are to where they need to be as quickly as possible.

The Bottom Line

Readability formulas are useful tools, but they should never make instructional decisions on their own, and they should never be used to limit or assign a narrow band of books for readers.

Use them as one piece of evidence alongside oral reading, fluency, vocabulary knowledge, comprehension monitoring, and your professional judgment.

When we look beyond a single number, we gain a much clearer picture of what our students need. That means we can provide the right support, increase text complexity with confidence, and help older struggling readers build the skills they need to tackle grade-level text successfully.

Read On…

If you would like more information about matching books to readers, check out How to Match Books to Students and Engage Struggling Readers