There are a number of important and excellent resources to learn more about the voice and singing pedagogy. This is a collection of a few resources that we have had experience with and are happy to recommend to you.
The National Association of Teachers of Singing has been publishing the Journal of Singing since 1944 covering topics related to singing pedagogy and research. The content tends to be more pedagogy articles than new research.
The Voice Foundation has published the Journal of Voice since 1987. It is a peer-reviewed medical journal focusing primarily on voice science, voice medicine and surgery, and issues pertaining to speech language pathology. This journal can be very challenging to read and articles are normally most focused on medical research.
Get Vocal Now is the work of Kerrie Obert one of the leading voice researchers and pedagogues. Get Vocal Now features several excellent mini-courses on vocal anatomy and pedagogy.
The Bulletproof Musician is primarily focused on improving practice and performance. Dr. Noa Kageyama is a performance psychologist and lecturer at The Juilliard School. The blog on the site is a treasure trove of information. Personally, I have not tried any of the courses, they can be applied to vocalists but are set up for instrumentalists.
Estill Voice is how I got started on this magical voice science journey. The level one and level two courses are an excellent introduction to an evidence-based pedagogy method. Level one in particular will provide a well rounded education in vocal anatomy. Unfortunately, Estill Voice's curriculum may not reflect the latest in voice science. That being said, the majority of the content is excellent.
Vocal Power Presents with Deric Rosenblatt is an interesting resource. Deric is a New York based teacher with a studio of A-list performers. Vocal Power Presents is a collection of lessons/interviews with these amazing performers. This is a great way to get ideas for your own lessons. The caveat I'd like to provide is that all of these students may be significantly more advanced than your students.
The Vocal Pedagogy Institute at Westminster Choir College is an excellent opportunity to learn from some of the greatest voice pedagogues and researchers in the world. The institute is available in-person and virtually and can be taken for graduate credit if desired.
The CCM Summer Institute at Shenandoah University offers a large number of courses in-person and virtually. Shenandoah faculty and guest lecturers offer an outstanding learning opportunity. Courses can be taken for graduate credit if desired.
Appcompanist is probably the most used app in my lessons. Featuring over 8,500 songs it is one of the most robust accompaniment providers on the market and is available with various subscriptions on iOS and Android. With each track you can adjust the Key, Tempo, and even add or remove melody notes.
Musical Theatre Practice Tracks has a lot less than Appcompanist but it has several full shows including tracks with melody parts. This can be an excellent place to check if you are in need of tracks for a whole show.