Regarding measuring children for violin or viola, there are two methods but the second probably works better and is more exact.

At one time what we did was to stretch the child's left arm under the instrument, and have them grasp the scroll with their fingers wrapped around the scroll. If the elbow was slightly bent but not too bent or too straight, it was a fit.

However, a more reliable method is to stretch the child's arm straight out under the instrument, and under the scroll, and if the instrument's scroll ends flush with the pulse, it is just right.

According to the build of the student, it can be a little shorter or longer.

A sturdy child can take a little longer; it will mean less bend at the elbow when they play--which is tiring but can be tolerable--but if the candidate is weak, then better not, and one chooses rather a little shorter instrument.

This rule is for kids during the time they grow, i.e. until early teenage.

For "grown ups" it no longer applies. Violins come usually short and violas usually long.

Connie Sunday: Freelance studio musician, strings and piano teacher, author of Violin FAQ and numerous essays in violin pedagogy. Further information can be found at connexions.