I tend to teach by having students work on a specific piece of music or a composition project, and I allow them to choose what kind of project they'd like top pursue. I then supplement this main project with background historical, analytical, and practical tools that help them achieve their educational goals.

Here are some resources I like to use depending on the type of instruction:

For Piano - Belá Bartók's Mikrokosmos, The Ana Magdelena Bach, Etudes by Friedrich Burgmüller, Stephen Heller, and Frederic Chopin

For Trumpet - Brass Tactics by Chase Sanborn, Arban's Trumpet Book

For Guitar - Takemitsu Etudes