There are so many theory books and resources for piano players, but there are not many relating to the violin player. Does a violinist have to have a basic understanding of the keyboard, before they can start to look at the building blocks of music, or is there another way?
I started learning the keyboard before picking up the violin and readily acknowledge the foundation my teacher set to helping me understand music. I am a violin and viola teacher and not all of my pupils are playing keyboard instruments. What do I do?
There are many elements that can be covered without the instrument - musical alphabet, rhythm, metre, time signatures. Things get a little trickier when it gets to key signatures.
For those of us who like the games approach, there are a number of websites with some fabulous games - perfect for group lessons!
Susan's games (key signatures are further down the page) are brilliant for younger children. http://susanparadis.com/catalog.php?site=piano-teacher-resources&type=Games§ion=5&level=x&subtype=x&subtype2=x

I also rely on the advice and creative input of classroom teachers. Teacher pay teachers has a large number of free downloads relating to different elements of music
http://www.teacherspayteachers.com/Browse/Price-Range/Free-Downloads/PreK-12-Subject-Area/Instrumental

For those of us teaching using semibreve, quavers etc there are UK based websites and resources we can draw upon http://www.teachingideas.co.uk/music/contents.htm

I don't think staying at the piano is completely necessary. Every instrumentalist needs an understanding of how music is structured. Whether this is done by the string teacher, or a theory/piano teacher is up to the teacher and the student (plus the wider family).
If anyone has some wonderful teaching methods for teaching younger children theory relating to the violin, I would be most interested in hearing your thoughts and ideas.