Stand infront of the elevated side of this exhibit. Allow the ball to travel along the slope from the top using the guide provided.

What did you observe? 
The ball hits the curved surface wall at the lower end and bounces towards the hole provided. Try the same for multiple times by changing the position of the ball. The ball hits the curved wall and bounces towards the hole for all the attempts.

The science behind it :
The lower wall is parabolic in shape and the hole is positioned at the focal point of the parabola. Hence the ball always bounces towards the hole. If light or sound waves are beamed in the parabolic surface, they will converge at the focal point.