$$ Students are given a student number when they join the school. This is stored along

with their name, date of birth, and the date they joined the school.

$$ Instructors are given an instructor number, the date that they start working as an

instructor must be recorded, along with their instructor status $($compensated or volunteer$).$

$$ An instructor may be assigned to teach any number of classes, but each class has one

and only one assigned instructor. Some instructors, especially volunteer instructors, may not

be assigned to any class.

$$ A class is offered for a specific level at a specific time, day of the week, and location.

For example, one class taught on Mondays at $5$:$00$ pm in Room #$1$ is an intermediate$-$level

class. Another class taught on Mondays at $6$:$00$ pm in Room #$1$ is a beginner$-$level class. A

third class taught on Tuesdays at $5$:$00$ pm in Room #$2$ is an advanced$-$level class.

$$ Students may attend any class of the appropriate level during each week so there is no

expectation that any particular student will attend any particular class session. Therefore, the

actual attendance of students at each individual class meeting must be tracked.

$$ A student will attend many different class meetings; and each class meeting is

normally attended by many students. Some class meetings may have no students show up for

that meeting. New students may not have attended any class meetings yet.

$$ At any given meeting of a class, instructors other than the assigned instructor may

show up to help. Therefore, a given class meeting may have several instructors $($a head

instructor and many assistant instructors$),$ but it will always have at least the one instructor that

is assigned to that class. For each class meeting, the date that the class was taught and the

instructors$$ roles $($head instructor or assistant instructor$)$ need to be recorded. For example,

Mr$.$ Jones is assigned to teach the Monday, $5$:$00$ pm$,$ intermediate class in Room #$1.$ During

one particular meeting of that class, Mr$.$ Jones was present as the head instructor and Ms$.$ Chen

came to help as an assistant instructor.

$$ Each student holds a rank in the martial arts. The rank name, belt color, and rank

requirements are stored. Each rank will have numerous rank requirements. Each requirement

is considered a requirement just for the rank at which the requirement is introduced. Every

requirement is associated with a particular rank. All ranks except white belt have at least one

requirement.

$$ A given rank may be held by many students. While it is customary to think of a

student as having a single rank, it is necessary to track each student$$s progress through the