Fluency is the ability to read text accurately, fluently/smoothly and with expression.  When I explain fluency to children, I say their reading should sound the same as when they're talking with friends (natural, with expression, and NOT like a robot or choppy).  Fluent readers are able to make sense of what they're reading so that they group words together properly and read with expression.  Below is a link to each grade level's quarterly fluency goals (which haven't changed from the 2017-18 school year).  It's important that children read at the expected rate so they maintain comprehension and are able to complete reading-related tasks within a reasonable amount of time.

This is especially important when referring to informational text (such as science and social studies).  Typically, students' fluency rates decrease when faced with informational text.  Previewing, studying and mastering content-specific vocabulary will help increase students' reading rates with informational text.  The same as with fictional literature, readers must use effective reading strategies to comprehend material; these strategies include (but aren't limited to):

• Making mental movies of information in head (visualization)
• Making connections (associate new terms/vocabulary with already-mastered information)
• Illustrate concept(s) in own words (through text or pictures)
• REREAD for better understanding
• "Teach" to someone; if someone can clearly explain and teach a concept/term then he/she has learned it
• Kinesthetic learners - get up and start moving!  Connect concepts to movements or "act out" new information to strengthen comprehension

Fluency Goals 2017-18.pdf
 

For additional information regarding fluency, visit: http://www.readingrockets.org/teaching/reading101/fluency