Basic Objects and their behaviors (Brainstorming):

  Ball           Paddles          ScoreBoard        Net
  ====           =======          ==========        ===
  ChangeSpeed    MoveUp           Init              Draw        
  BouncePaddle   MoveDown         AddPlayer1        Erase
  BounceWall     CheckCollision   AddPlayer2        Update
  Reset          Init             HasEnded
  Draw           Draw             GetWinner
  Erase          Erase            Draw
  Update         Update           Erase
                                  Update


  Numbers
  =======
  Draw 
  Erase
  SetNumber



Ball, Paddles, ScoreBoard, and Net all share:
   Draw, Erase, Update
Therefore, these all have a common base class:
   GameElement