Authentic feedback is essential for students to know clearly what the expectations of the instructor are. It should be positive, encouraging, constructive, clear, and concise. The instructor should always include helpful resources in the feedback to provide students remedial assistance. It is imperative that the instructor grade assignments promptly and provide feedback immediately, so students can make progress through the remediation. There are several different ways for an online instructor to deliver feedback: by text, phone call, voice message, audio, or email.
Here is a student work sample and accompanying feedback.