nested_class_associations.rb

class District
  has_many   :leagues
  has_many   :seasons, :through => :leagues
  # has_many :teams ???
  
end

class League
  belongs_to :district
  has_many   :seasons
  has_many   :teams, :through => :seasons
  
end

class Season
  belongs_to :league
  has_many   :teams
  
end

class Team
  belongs_to :season

end