The Expanding Universe: Balloon Model

 On a flat, not-yet-inflated balloon, mark a series of points using a permanent marker.  You may wish to make some of the points closer together and others farther apart. 

These marks represent parts components of the universe.  You may wish to have students measure the distance between points to make it more quantitative, of you may wish to just keep it a visual activity. 

 As you begin to inflate the balloon, the points mover farther and farther away from each other.  The universe is expanding and distance between points is growing.