I tried to make 2 balls collide and bounce of each other in believable directions. This experiment failed due to some unknown reason, I think. Problems could have been due to : the degrees the ball turns when the radius's touch, how far each ball jumps when their radius's touch, Howard and Ken making an error or some unknown bug.

There are some explanations that are hard to get into your head. What modeling4all does is make you visualize things, e.g, biology-To demonstrate how bacteria multiply when they reproduce, Geography- How the population lives. "sugarscape" is a great visual demonstration to show what happens  to the population over time. Why people move from place to place? Why people have in areas of low sugar concentration have a shorter average life span? etc. Earthquakes. Physical education- team formations in football, rugby etc. Business- The global market changing on a daily basis.