class Season(models.Model):
    season = models.CharField(max_length=4)
    start_date = models.DateTimeField()
    end_date = models.DateTimeField()


class Challenge(models.Model):
    season = models.ForeignKey(Season, on_delete=models.CASCADE)
    name = models.CharField(max_length=255)
    start_date = models.DateTimeField()
    end_date = models.DateTimeField()

class Attempt(models.Model):
    challenger = models.ForeignKey(User, on_delete=models.CASCADE)
    challenge = models.ForeignKey(Challenge, on_delete=models.CASCADE)
    points = models.IntegerField(default=0)

Season(season='2019',
       start_date=...,  # some date object
       end_date=...,  # some date object
)

Challenge(season=1,  # represents season object above
          name='Challenge 1',
          start_date=...,  # some date object
          end_date=...,  # some date object
)

Challenge(season=1,  # represents season object above
          name='Challenge 2',
          start_date=...,  # some date object
          end_date=...  # some date object
)

Attempt(challenger=1,  # represents user object
        challenge=1,  # represents challenge 1 above
        points=5
)

Attempt(challenger=2,  # represents user object
        challenge=1,  # represents challenge 1 above
        points=10
)

Attempt(challenger=1,  # represents user object
        challenge=2,  # represents challenge 2 above
        points=5
)


Attempt(challenger=2,  # represents user object
        challenge=2,  # represents challenge 2 above
        points=10
)