Check out some videos and activities/games to help you practice reading notes and rhythms. You'll be a pro reader in no time!
The Basics
Two-Minute Music Theory - a YouTube playlist that breaks the basics of music theory down into 2-minute chunks
Musictheory.net - A website with animated lessons to teach music theory from the basics to quite advanced stuff. They also have exercises to practice.
Notysing - An app that teaches sight-singing! Be able to read music and sing it before hearing it. Has a similar structure to DuoLingo, but with music.