title: How can I get this method return this argument?
body: <p>I need to have <code>add_student</code> add multiple students to the array <code>grade</code>. The method should add multiple students to the array and assign them to <code>grade</code> or the key in the hash. </p>
  
  <pre><code>class School
    def initialize(name)
      @name = name
    end
  
    def roster
      @roster ||= {}
    end
  
    def add_student(student, grade)
      roster[grade] = []
      roster[grade] &lt;&lt; student
    end
  
    def student_grade(grade)
      return students
    end
  end
  </code></pre>
  
  <p>I do not understand why <code>add_student</code> does not add multiple arguments. I get an error that it returns only one argument or <code>nil</code>.</p>