SmartMusic is an effective, fun, and unique way to practice at home. Students see which notes and rhythms they played correctly/incorrectly, receive a performance score, and hear their recording. SmartMusic includes a metronome, tuner, and the ability to loop sections! I HIGHLY encourage any student to practice using this program.
MusicTheory.net is a great website that has lessons, exercises, and tools to help you learn basic music theory.
Metronome Online is a great free online metronome that can help you keep a steady beat while you practice musical passages. Here is how I recommend using a metronome in 3 easy steps:
Amazing Slow Downer is an awesome tool that slows down songs so you can transcribe and practice along with your favorite artists!
Interested in composing and/or arranging music? MuseScore is an excellent music notation program that you can use and it's free!
Tuners: using a tuner while you play will help you learn how to play in tune. You can find free versions of tuner apps in any app store or use a browser-based tuner like this. You can also purchase a tuner from most instrumental music stores.