MusicRacer.com is a fun website that can help students practice note names, fingerings, and music terminology. These are very basic review questions, but can help students to be more successful on their instruments. Select the game you'd like to play and scroll down till you see your instrument! (Violin, Viola, Cello, or Bass). Click here for instructions that can help with the notes/fingerings for musicracer.com.
The below links offer practice with reading note names on either the Treble Clef, Alto Clef, or Bass Clef staff.
RhythmTrainer.com is a free website for learning and practicing rhythm. There are two types of exercises: A Mode, where you click in the rhythm that you hear, and B Mode, where you see a rhythm and choose a sound that matches.
Viola the Bird is a free website that allows students to control the bow of a string instrument and create music similar to how we would play our own instruments. There is a freestyle version or a concert version which allows students to play different arrangements of Classical Music literature.