The comment I most commonly receive from parents is 'I don't know anything about music, so I'm no help to my child'. Well, here are some things you can do to help your child improve in music, having little to no knowledge in music:
1) Encourage your child to bring home their instrument as often as possible. The best way to improve in music, is to practice. The biggest struggle students have in music is reading the notes. With proper practice, known as the 'Song Learning Process', students will improve this skill through experience. More consistent practice is BY FAR more effective than a 'cram session' of practicing extensively right before a playing test. NOTE: See Instrument Sign-Out.
2) Sit and listen to your child practice. Playing for an audience is a very 'nerve-racking' experience for some students. By performing for an audience that a student is more comfortable with, will help reduce the anxiety a student faces when performing in music class.
3) Clap a beat for your child. If a metronome is not available, you can simply clap a steady pulse while your child is practicing. This will help encourage them to keep the rhythm of a song accurate, thus helping them learn how to read music more accurately. There are free metronome apps out there that can be downloaded. There is one called Steinway metronome that I recommend.