I'm not familiar with Lexiles but I found this on hoagies:

"Another reading level scale is the Lexile Level. Using the "Search" function on this site, you can determine the Lexile level for various books. Lexile Measure is a number indicating the reading demand of the text in terms of the semantic difficulty (vocabulary) and syntactic complexity (sentence length). The Lexile scale ranges from 200 to 1700 Lexiles, although actual Lexile measures can range from below zero to above 2000 Lexiles."

They provided this link that explains it more.

http://www.lexile.com/DesktopDefault.aspx?view=ed&tabindex=1&tabid=49&tabpageid=545

Sounds like he is doing great!!!! smile