I found Noteflight fairly easy to use. Teachers looking to use this tool with their students can take comfort in knowing that tutorial videos, FAQ’s and help forums provide excellent help and support to users of varying computer expertise. Creating a free account takes only a few minutes. Students can easily access their work from a computer at school, as well as at home. This tool can readily be used in music theory classrooms as both an instructional aid and as a tool for students to do part writing or other assignments. A band director might use this tool to have students transpose parts or to transcribe a solo for jazz band.
I can already tell that my favorite use of Noteflight will be that I can have students transpose their parts! Next time you need a student to cover or double another part, have your students try inputting the notation themselves. Noteflight even has a transpose feature!