Determining The 'grade' Level Of Music For Youth?

I haven't written music specifically for youth/education, but I've noticed that in that field, many composers will characterize the difficulty levels of their pieces as "grade 3," "grade 4," etc.

Are there lists online with specifics for each "grade" standard?

How does one quantify difficulty level when there are so many factors?

(If there are ensemble-specific lists, I'm primarily interested in finding out the standards for string ensemble music -- and music for solo instrumentalists.)

Thank you.

A very imperative question, but not one to boggle down and to worry about. The level of difficulty arises from how demanding and playability a composition may be in accordance to the elements that a student is learning at the given time. Trust me, I took Piano for 10 years. The words beginners, intermediate and advanced are often more used than grades. Along with these, the words early, middle, and late are used. This helps the pupil and teacher to choose the proper piece that best fits the student's ability. furthermore, these suggest how hard the composition will be to play for the performer.

For strings, I have a bit of an idea as to how they are graded. They are based on technical difficulty, rhythmic complexity, how easy the music is to "put together", and the key signature.

Level one and two pieces are very simple and don't involve a lot of counterpoint. The key signatures are simple, and the keys are ones that are easy for strings to play in, such as C, G, and D major. They typically require minimal shifting if any.

Level three pieces require some shifting into third position mostly for the first violins. They can sometimes venture into flat keys.

Level four is the highest level I have seen. This level can feature shifting for all parts into third position or higher. First violin parts sometimes go much higher. Advanced rhythmic patterns can also appear such as hemiolas, artificial groupings, and extensive changes in time signature. These can venture into more far away keys.

Here is a website with arrangements for string orchestra that includes grade level, score samples, and recordings.http://www.tempopress.com/dackoweditions.asp

Hope this helps :)