This informational site for teachers and students explains the importance of a letter of apology. Then the article articulates the types of information to include in friendly/personal apology letters and in formal/business apology letters.

At the end of this instructional activity, learners will demonstrate the use of commas, clarifying questions, and a friendly letter format by sending an email. Email is part of student's lives, and it is part of the digital landscape...

This student and teacher-friendly site contains the purpose of writing a cover letter. In addition, the article discusses the format of a good cover letter and elements to include in a good cover letter.