school-domain.rb

class School
  attr_accessor :name, :roster

  def initialize(name)
    @roster = {}
    @name = name
  end

  def add_student(student_name, grade)
    #refactored after seeing others' work
    self.roster[grade] ||= []   
    self.roster[grade] << student_name

    #my first version (also passes)
    # if self.roster.has_key?(grade)
    #     self.roster[grade] << student_name
    # else
    # self.roster[grade] = [student_name]
    # end
  end

  def grade(grade)
    self.roster[grade]
  end

  def sort
    self.roster.each do |key,value|
      value.sort!
    end 
  end

end