The Lexile program is often touted as an alternative to basing a child's perceived reading ability solely on less personalized standardized test scores or offhanded guesswork by the education system or parents. After a score is calculated, the teacher and involved education team can encourage the child to read at or slightly above the range that is assigned. This ensures that the child will learn at her own pace without becoming stuck at a particular reading level.
The majority of textbooks used in the United States education system have been assigned Lexile scores and are therefore candidates for assigned or recommended supplemental material in and outside the classroom. The majority of texts from books, magazines or other sources can be assessed fairly easily for a Lexile chart. The system can be used to rank short passages from texts as well. In this regard, any text that is longer than a couple of sentences can be introduced into a child's curriculum based on his or her Lexile chart.
While there is no direct correlation between Lexile scores and grade levels, a Lexile chart can determine whether a student falls into the average percentile for his grade level. The Lexile system establishes a range for grade levels one through 12. For example, grade one scores range from 140L to 300L, while grade two ranges from 140L to 500L. It is this overlapping quality that is believed to help the flexibility and personalization of a student's reading ability. The basis for measurement of a textile chart takes into account the median level of the grade level that the student should be reading. In this regard, only student's scores that are between the 25th and 75th percentile are used in devising the measurement system. Any student can receive a Lexile score, but only students reading in the median range are considered for the overall calculation criteria in the system.
The Lexile measurement of a specific text is based on two general categories -- the length of sentences and word frequency. Texts with longer and more complex sentences per section tend to receive higher Lexile scores. Texts with lower word frequency also receive higher scores because the lack of repeated language suggests that the text employs significantly more complex concepts and word combinations.
While the Lexile chart can be used effectively as an assessment tool, it is recognized by educators as a limited system. Other factors like the overall maturity and behavioral profile of the student have been shown to be important when assigning or encouraging the use of material. Prior knowledge and cultural receptivity are other factors that are considered in assessment as well.