It seems there are many grading systems to indicate the difficulty of a piece of music. They are based on range, key signature, time signature, technique, musical skills and musical maturity.
National Flute Association, USA
One of the numbering systems used by the National Flute Association, is used in the “New Music Review” column for the organization’s magazine, The Flutist Quarterly .
1 – First-year beginners
2 – Easy, for second or third year
3 – Intermediate students, Jr. High or High school
4 – Advanced High School musicians
5 – Difficult – for college players
6 – Very difficult music for advanced college players, professionals
They use a different grade level scheme in their publication: Selected Repertoire and Studies a Graded Guide. This system uses the letters A – J to indicate the different levels of difficulty. Pages 13 – 24 of this guide pertain to the descriptions of the levels. Example:
Criteria Chart: Level A
Pitch and Key Range G1–A2
Occasionally extended to D1–D3
Major and minor key signatures using up to 1B; (occasionally 2B) & 2 b.
Limited use of accidentals beyond key signature. Possible
use of accidentals within composition to establish key en
lieu of key signature.
Rhythm and Meter Basic rhythms using w d h q n Yin @, #,
and $. (These are defined earlier in the guide.)
No syncopation, dotted rhythms, or partial beat pickups.
Restricted use of ! and C. Cut-time may be
treated as $.
Articulations Basic single tonguing techniques. Simple slurred, legato,
and staccato articulations.
Musical Symbols Treble clef pitch notation; accidentals; symbols for
repeat, D.C., D. S., and dynamics.
Pedagogical Focus Basics of position and posture, tone production, fingering, articulation, and notation reading (where applicable). Rudiments of playing softer and louder (p and f ).
Performance of short phrases and successful handling of
predominantly conjunct melodies with occasional leaps up to one octave
Selected Repertoire: Level A
Selected Collections
Arnold Easy Flute Solos, Series 83 (AMSCO) [ABCD]
Bullard Party Time! (ABRSM) [AB]
Harris/Adams Music Through Time, Flute, Book 1 (Oxford) [ABc]
Isacoff Skill Builders for Flute (Schirmer) [ABCDe]
Pearce/Gunning The Really Easy Flute Book (Faber) [ABcd]
Steensland/Weber The Flute Soloist, Level 1—Elementary
Jennifer Cluff, Canadian Flutist and Teacher
Jennifer Cluff includes a very detailed, and informative outline on her site, which shows the Royal Conservatory grading system in Canada. It lists the performance requirements for specific grade levels. Also included are the related grade levels for the United Kingdom, Fluteworld (USA sheet music purchase resource) and ABRSM . (The examinations in London, UK)
CHART of flute grading levels example:
Level 1. Beginner and Level 2. Beginner-Novice
________________________________________________
Royal Conservatory: Grade, 2 Canada
ABRSM Grade 1 – Guildhall Grade 1-2 UK – Fluteworld Level ONE
– Low D to D3 (two ledger line D)
– Key signatures up to 3bs and 3#s read easily
– dotted rhythms and 1/16th notes played correctly
– 3/8 and 6/8 time signatures read correctly
– ability to clap-count-recognize basic rhythms
– sightreading and/or improvising done regularly
Example of solos: Grade 2: Minuet from J.S. Bach’s B-minor Suite no. 2 or Minuet from Dance of the Blessed Spirits by Gluck or Schubert’s Moment Musicale from “40 Little Pieces” or Dick’s SunShower orMendelssohn’s Andante Espressivo or Ravel’s Pavane pour une Infante Defunte.
Example of Etudes: Gariboldi ‘Thirty Easy and Progressive Studies’ (These etudes are printable from CDsheetmusic for flute).
Mozart – Performance .mp3 with grading
Jennifer Cluff also has a link to her comments on grading using Mozart Andante in C which is in .mp3 format as an example.
Leonard Garrison, Performer and Teacher, Idaho, USA
For those using the National Flute Association Repertoire Guide system of grading, which uses the letters A-J, here is a link to repertoire that fits that lettered grading system: Leonard Garrison NFA Graded repertoire