Lexile Oral Reading and Readability Measures

The Lexile Framework for Oral Reading features two measures:
  • The Lexile oral reading measure (student measure) represents how well students can read English-language passages aloud fluently and accurately.
  • The Lexile oral readability measure (text measure) represents the oral reading challenge of a piece of English-language text.
Both measures are reported on the same developmental scale, the Lexile scale.

Lexile Oral Reading Measures

The Lexile oral reading measure for a student is obtained by having a student read one to three short passages aloud and submitting the audio files to the Oral Reading API (usually via a partner who has incorporated the software into their oral reading program). The Oral Reading API uses the following three features to estimate student oral reading measures:
  • Words Correct Per Minute (WCPM). This predictor, a combination of Accuracy and rate (an aspect of automaticity), is defined as the number of correctly read words divided by the length of the performance in seconds divided by 60. So, if 50 words were read correctly in 30 seconds, the WCPM would be 50/(30/60) = 50/0.5 = 100.
  • Accuracy. Passage-Level Accuracy ranges from 0 to 1 and is defined as the number of correctly read words divided by the number of words attempted by the student. If a student reads the first 50 words of a 100-word passage, reads 45 of those 50 words correctly, and makes an error on 5 of those words, then the Passage-Level Accuracy will be 0.90.
  • Oral readability of the text (i.e., Lexile oral readability measure). A text’s Lexile oral readability is determined by the Lexile oral readability analyzer using a model based on text characteristics related to sub-word units, word-level features, sentence-level features, and discourse-level features.
In general, as the text becomes more difficult to read aloud, the student is more likely to read more slowly and/or less accurately. An empirically derived formula explains how student reading performance varies depending on text readability:
  • At 95% accuracy, for every 100L increase in student ability, we expect 14 WCPM increase.
  • At 95% accuracy, for every 100L increase in text difficulty, we expect 9 WCPM decrease.
For example, if a student with a Lexile oral reading measure of 600L independently reads a text with an oral readability measure of 800L, then the student would likely read at:
  • 77 WCPM with 95% accuracy, or
  • 83 WCPM with 90% accuracy

Lexile Oral Readability Measures

The Lexile oral readability measure is calculated using an algorithm based on six different features of the text when determining its oral readability measure of English-language text. When evaluated during the development of the Lexile oral readability measure, these six features were the most effective in predicting how well students could read a passage orally. They include within-word level, word level, and sentence level features to capture the overall challenge of reading a text aloud.
  • Within-word features
    • word decoding demand
    • syllable count
    • predictability of the sound-symbol relationship of the words in the passage (e.g., loop is more predictable than teach, which is more predictable than true).
  • Word-level features
    • age of acquisition
    • word rareness
  • Sentence feature
    • log mean sentence length (e.g., longer sentences are often more complex and challenging for students to read aloud)

The Lexile oral readability measures were calibrated and reported on the Lexile scale so they could be directly compared to Lexile text measures. For example, if a passage has an oral readability measure of 500L and a Lexile measure of 300L, then the task of reading this text orally is 200L more challenging than reading and comprehending the text.

The oral readability of texts students typically encounter in grades K-3 are shown below. These measures are provided to assist with the interpretation of oral readability measures. The data come from a study MetaMetrics conducted on the oral reading difficulty of texts that students typically encounter in Grades K-3. The analyses drew passages from six popular oral reading fluency tests (e.g., DIBELS Next, DRA, and easyCBM) as well as leveled readers and passages drawn from books and other materials from 20 top publishers (e.g., Capstone Press, Rigby, Sundance, Scholastic, and Pearson). Materials were selected to include common types of early reading materials. These included decodable and sight-word-based texts and texts with more difficult or complex words that will be read orally by students but with support through shared reading or repeated reading. More than 3,000 passages were included in the study.

Table 1. Typical Lexile oral readability measures by grade.
Grade N 25th 50th 75th
K 466 110L 260L 430L
1 1067 190L 330L 460L
2 836 380L 480L 580L
3 681 510L 620L 770L

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