Django Model Design

from django.db import models

# Create your models here.


class Student(models.Model):
    STD_CLASS=(
        ('6','SIX'),
        ('7','Seven'),
        ('8', 'Eight'),
        ('9', 'Nine'),
        ('10', 'Ten'),
        ('10X', 'ExTen'),

    )

    GROUP_NAME = (
        ('S','SCIENCE'),
        ('H','Humatics'),
        ('B','Business'),
        ('G','GENEREL'),
    )
    std_name=models.CharField('Student Full Name',max_length=100)
    std_class=models.CharField('Student Class',max_length=2, choices=STD_CLASS)
    std_roll_number=models.IntegerField('Roll Number')
    std_group = models.CharField('Student Group',max_length=1, choices=GROUP_NAME)
    std_gpa = models.CharField('Student GPA GRADE',max_length=3, blank=True, null=True)
    std_gpa_point = models.DecimalField('Student GPA Point',default=0, max_digits=3, decimal_places=2)
    std_total_marks = models.IntegerField('Student Total Marks',default=0)


    def __str__(self):
        return self.std_name


class StudentSubject(models.Model):
    subject_name=models.CharField('Subject Name',max_length=50)
    subject_full_marks=models.IntegerField('Full Marks')
    subject_marks=models.IntegerField('')

    #add forign key
    student=models.ForeignKey(Student,on_delete=models.CASCADE)

    def __str__(self):
        return self.subject_name