Circle of Fifths
Treble, Alto, Tenor and Bass Clef Clef http://openmusictheory.com/keySignatures.html
Fingering Charts
Violin (1st-7th position) http://www.violinonline.com/fingeringchart-advanced.htm
Interactive Finger Placement page: http://www.violinonline.com/fingerplacement.htm
Viola (1st-7th position) http://www.violaonline.com/violafingeringchart.htm
Cello (1st-7th position) http://www.celloonline.com/cellofingeringchart.htm
Bass (1st-7th position) https://www.stringbassonline.com/bassfingeringchart.htm
Metronome http://www.metronomeonline.com/
Music Dictionary http://dolmetsch.com/musictheorydefs.htm
A Musical Glossary for Kids https://www.theaterseatstore.com/blog/musical-glossary-kids
Music Theory Links https://www.aaastateofplay.com/a-musical-playground-for-kids-music-theory-lessons/
Pedagogical Info
Violin https://www.violinonline.com/
Viola http://www.violaonline.com/
Cello http://www.celloonline.com/
Bass http://www.stringbassonline.com/
Bowing http://artofthebow.com/movies/
Rhythm, Note Reading, Key Signature Lessons http://www.musictheory.net/lessons
Rhythm, Note Reading, Key Signature Drills http://www.musictheory.net/exercises
Supplies http://www.sharmusic.com/
http://www.thecreativemusiccenter.com/
http://www.musiclearningcenter.org/