How should I structure this?

No. Kidding check has many through in the docs. http://laravel.com/docs/5.1/eloquent-relationships#has-many-through

@jlrdw Completely forgot about that. Thanks!

From your requirements, I see that each grade belongs to an assignment. I would have the following models.

// App/Student.php

class Student extends Model {
    public function assignments() {
        return $this->hasMany('App\Assignment', 'user_id');
    }

    public function grades() {
        return $this->hasManyThrough('App\Grade', 'App\Assignment');
    }
}

One model for the Assignments

// App/Assignment.php

class Assignment extends Model {
    public function grades() {
        return $this->hasMany('App\Grade');
    }
}

and finally a model for Grades

// App/Grade.php

class Grade extends Model {
    public function assignment() {
        $this->belongsTo('App\Assignment');
    }
}

You can access the grades directly from the User/Student model, or you can fetch an assignment and get the grades for that specific one.

Mind you,

Admin, Teacher, n Student r all User..

So there shouldn't be anything like StudentModel, AdminModel blah blah

Because looking at it, student , admin, teacher are just roles a user can belong, So pls let structure the relationship well,

Am not too good at structuring too cos that what's am trying to work on improving myself , and am always following relationship discussion to learn

That can get tricky, a student has the assignment. Later a student wants to view their grade. But you are better of keeping the relations as simple as possible. teacher->student->assignment. Grades isn't a separate table, it could be in students or assignments table depending on how you want it. I wouldn't have a table just for grades.

@jlrdw, pls give the way you will structure it, let see the code.

Never thought that this would turn into a bigger discussion. Thanks for all your help!

Feel free to keep discussing how you would do it :-)

If each student receives an individual assignment then you don't need a grades table, however I don't think that's the case.

Multiple students will receive the same assignment and each student can receive a different grade for that specific assignment. Therefore a separate table to store the grades for each student for each assignment is required.

A good read on relationship depth http://laravel.io/forum/05-12-2015-has-many-through-relationship-depth
@fetch404 I like your reply

Feel free to keep discussing how you would do it :-)

@bikerboy Exactly. Thanks!

Does anyone know how I could use pivot tables for this? This really puzzles me.

Why do you need a pivot table?

If you can do this without a pivot table I would once you start getting in the pivot tables things get more complicated. I have done complex relations before and I have never needed a pivot table. Always try to look for a simple solution as possible.

Thanks, everyone. I'll post pictures when it's working!