The ability to read independently is one of the most important skills for a student to learn. But if you ask a student to read a book beyond her reading level, you set her up for frustration and failure -- and too much failure will turn a learner off from reading, crippling her lifelong learning potential. Set up your student for success through using Lexile scores, a framework for determining a text's difficulty for any reader.

Find the Lexile Level

Know what "Lexile" means. The Lexile Framework for Reading measures the difficulty of texts based on two parameters: length of sentences within the text and frequency with which words repeat within the text. The shorter the sentences and the more often the words repeat, the easier the text is, and the lower its Lexile score will be. The longer the sentences and the less often the words repeat, the harder the text is, and the higher its Lexile score will be.

Have your student take a Lexile Measurement test. If he is in a public school, such tests are administered by the state (frequency varies by state). Contact your school's guidance counselor or records keeper to see if your student already has a Lexile score on file. If he is home-schooled, buy an appropriate test at the Lexile website.

Interpret the results of the test. The scores range from 200 (for the most rudimentary readers) to 1700 (for highly advanced readers). Scores are based purely on reading ability, not age or grade level.

Use the Lexile score for your student to pick out an appropriate book. A student with a 200 score should start with books like "Amelia Bedelia" and "Clifford the Big Red Dog." A student with a 1700 score can tackle Darwin's Theory of Evolution.

Remember that a book at your student's Lexile level will be challenging, but still accessible. According to studies, the student will understand roughly 70 percent of the text. Your student will be able to read without getting too frustrated while still picking up new vocabulary and sharpening reading skills.

Find the Lexile Score of a Text

Look up the title of the text in Lexile's database. Since 2009, publishers around the world have been providing Lexile scores for their publications. This includes most textbooks as well as many novels and magazines.

Upload a text sample (preferably 125 words long) to the Lexile Analyzer. The program is free to use and will give you a Lexile score for the text, plus the text's word count, mean log frequency and mean sentence length.

Remember that your student should ideally be reading a book at or within 50 points (above or below) her Lexile reading level. Too low, and the text will seem inane. Too high, and the text will seem impossible.