Trained music teachers often work in a variety of capacities, both privately and for groups, as well as teaching inside and outside of schools and other institutions. Most instructors will charge by the hour, sometimes on a sliding scale depending on class length and frequency. When an instructor works as an independent contractor, they should personally invoice their clients when requesting payment. If the arrangement with their client is ongoing, invoices should be sent at regular intervals (weekly, bi-weekly, or monthly).