Final answer:
A certified letter of classroom completion is given by the school's principal or department head in high school, or by the dean or registrar in college to mark successful course completion.
Step-by-step explanation:
A certified letter of classroom completion is typically awarded by an educational institution at the end of a course or program to signify that a student has successfully completed the required hours of study. In most cases, this certification is issued by either the principal or department head in a high school, or by the dean or registrar in a college setting. The document serves as formal recognition of the student's achievement and can be used for various purposes, such as applying for graduation or providing proof of education.