TheoryWorks II: Sight Singing & Harmony Essentials

Six weeks of one-on-one coaching to learn how to sight sing, hold down a tricky harmony, and navigate a music rehearsal.

We're not your average online course.
Find out about our mentorship approach.

Starts April 7

Six Week Mentor-Guided Course

Money‑Back Guarantee

You’re an actor who can already learn a piece of music on your own from the notation, but what happens when you're thrown a piece of music on the fly? How do you tune your ear so you can hold down a difficult harmony line and sing in parts?

TheoryWorks II is the second online course in our series on music theory for musical theater actors and professionals with 1:1 coaching. (Click here for the first course, TheoryWorks I,which teaches you how to understand complex rhythms, plunk out a melody on the piano, and read notes in your register with fluency.) In this course, we cover scales and keys, how to recognize intervals, why key signatures are built the way they are, how harmony works, ear training drills, and the way music is structured so you can anticipate what comes next — the key to sight singing with ease. You'll then learn how to use all this information to create your own competitive audition cuts, so you don’t have to rely on an expensive teacher or coach to create your cuts for you.

By signing up, you’ll receive weekly 1:1 coaching and feedback sessions from a theory expert who's also a working actor throughout the entire six-week course. All our coaches are working professionals and music directors living in New York City, and teach from our online course materials, written by NYC voice teacher and founder Amy Marie Stewart. Lifetime access to all learning materials, including lessons, video, animations, and audio examples, are included in the cost of every 6-week coaching package.


Music Theory for Working Actors

TheoryWorks is a company founded by voice teacher/actor Amy Marie Stewart and designed to help working actors gain the music and theory skills they need to succeed in today's competitive theatre world. TheoryWorks trains actors to be musically literate, autonomous, and confident. Sign up at to hear about new courses, tutoring sessions, bootcamps, and other projects on the horizon!

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  • Unlimited access to interactive and video content
  • Weekly feedback and support from an expert Soundfly Mentor
  • Membership in our growing online Slack community of students and mentors

Price $499

Become a more versatile singer with theory fundamentals

Feel more confident and powerful in your next audition, rehearsal, or performance with a better grasp on scales, harmony, and song structure.

Learn Scales & Keys

Situate yourself in your next song with knowledge of scales.

Master Intervals

Practice and master the secret sauce of sight singing.

Understand Harmony & Progressions

Become a more supportive vocalist by understanding how chords work.

Make Competitive Audition Cuts

Understand song structures so you can make your own cuts.
Are you an educator? If so, you can access educator discounts. !


Our expert mentors do whatever it takes to ensure that you achieve your musical goals for the course and leap forward in your learning.

Amy Stewart

Singer, Actor, Teacher
  • Founder of TheoryWorks
  • Published Backstage expert on music theory for actors
  • Educator whose students have appeared on Broadway, national tours, cruise lines, & more


Course Outline

  1. Start
    Section 1


  2. Start
    Section 2

    Major Keys

  3. Start
    Section 3

    Minor Keys

  4. Start
    Section 4


  5. Start
    Section 5


  6. Start
    Section 6

    Chords & Harmony

  7. Start
    Section 7

    Chord Progressions

  8. Start
    Section 8

    Song Form

  9. Start
    Section 9

    Making the Cut

  10. Start
    Section 10

    Final Project


Who is this course for?

This course is for current and aspiring musical theater professionals who want to feel more confident learning new music. Whether you're an actor who never learned to read music, a singer who didn't get a degree in musical theater, or a student who's felt behind in theory courses in school, this course is made specifically for working singers and actors, taught the way singers uniquely learn.

What will I learn?

You'll learn essential tools for improving your ear, holding a harmony, and sight singing a piece of music. No one becomes a musical expert (or, really, an expert of any kind) in just a few weeks, so the goal here is not that you'll be a flawless sight singer by the end of the course. Instead, you'll have a toolbox of methods to use while practicing and sight singing on the job. You'll also learn how to cut your own piece of sheet music for your audition book.

Are there any pre-reqs? 

You should already know how to read bass and treble clef, understand note values, be comfortable plunking your melody accurately at the piano, and be able to accurately teach yourself a piece of new music. If any of that sounds like something you could use help with, we highly recommend that you check out the first course in this series: Music Theory for Broadway Actors.

Is there a money-back guarantee? 

YES. If you sign up and the course isn't what you expected, we will give you a full refund as long as you tell us before the start of the second week. The reason that the second week of the course is a cut-off for our guarantee is simply because if we go past that deadline, our mentors will have likely put in a lot of time, energy, and effort already. 

We're also happy to move you to a subsequent session, if you end up not having as much time as you expected. Once again, let us know as soon as possible! 

What do I get as a Mainstage student? 

The Mainstage experience is built on our science-backed active learning model, which helps you learn more efficiently and effectively than typical online courses. The key difference is our mentorship approach — one-on-one coaching with a trained Soundfly Mentor who has extensive experience in the subject. When you sign up, we'll pair you with an expert who will tailor the course to your experience level, offer detailed weekly feedback on your work, answer any questions you have, help you blow past obstacles, and keep you on track to accomplish your musical goals.

You'll also get unlimited, lifetime access to all the course content — including in-depth lessons, activities with answer keys, quizzes, video tutorials, and downloadable resources — so you can review anytime and keep your skills sharp.

As an extra perk, you'll get lifetime access to our tight-knit musician community group on Slack, where you'll find peer-to-peer feedback and support, lots of inspiration, and fun, musical conversations with fellow Soundfly students, mentors, and staff.

What does it mean that the course starts on a specific date?

As soon as you purchase a course, you can begin exploring the course material immediately. On the start date, the session begins, which means you'll begin a guided experience that includes weekly activities, feedback from a Soundfly Mentor, and much more. This is intended to help you stay accountable and get the feedback you need to succeed. 

Will there be future sessions of the course?

Yes! Check back shortly for firm dates, or sign up for a Soundfly account to receive email updates about course dates and new course launches.