Consider a database application which provides a web$-$based platform where students can practice on tasks

assigned by the instructors. In terms of design, following are some major requirements:

$$ Instructors will first create their accounts. Relevant details for the instructors are: email, affiliation

and name.

$$ Instructors will create courses and add students to each course. Relevant details for courses are:

course code, term and year. Relevant details for students are: email and student ID$.$ Furthermore,

the system generates a system wide unique course$-$id for each course created.

$$ In Courses, Instructors will create one or more assignment and an assignment will consist of one

or more tasks. System generates a system wide unique assignment$-$id for each assignment created.

Assignments are always specific to a course, has a due date and a lateness penalty.

$$ In this system tasks are considered independent items and instructors may create tasks which are

not part of any assignment or course. Such tasks will be added to the instructor$$s question pool.

Each task has a system wide unique identifier.

$$ Instructors can also create tasks when they are adding tasks to the assignments, after creating an

assignment. The system automatically adds these tasks to the instructor$$s question pool.

$$ When creating assignments, instructors can also pick existing tasks from the question pool.

$$ A task when associated with an assignment, whether added from pool or created as new, is assigned

a max$\_$grade, a positive number. The students when attempt that task will get the score in the range

$[0-$max$\_$grade$].$

$$ Students will work on assignment$($s$)$ and consequently task$($s$)$ in that$/$those assignment$($s$).$ Student

submission$($s$)$ will be awarded a score; the total score of all the tasks in an assignment will be the

score of the student in that assignment. Students not working on an assignment or task will be

awarded $0.$ For each task submitted, the system also stores the time when student submitted that

task. There is no separate submission time for the assignments