Abacus The abacus can be used to ADD, SUBTRACT, MULTIPLY, and DIVIDE as well as work with sophisticated mathematical problems such as fractions and square root. The frame of the abacus has a series of vertical rods on which a number of beads are allowed to slide freely. A crossbar separates the frame into two sections – the upper deck and the lower deck. 

Elliptical Billiard Normally a billiards game is played on a rectangular table and winning requires technical skills. But in an elliptical billiard table, the player always wins. That is, when you hit the ball towards any direction it always goes into the hole. The elliptical shape of the billiard table makes the ball move this way. 

Parabolic Dish With your ear close to the ring, you can hear your friend from any part of the room. It is the parabolic shape of the dish that focuses sound onto the ring. The angle of incidence to the inner surface of the dish is equal to the angle of reflection. Thus, any incoming sound that is parallel to the axis of the dish will be reflected to the ring, which is the central point, or focus. 

Square Wheels Place the square wheel on the far left end of the bumpy road. Push the wheel to the right then let it go. Does the wheel roll along smoothly? Balance the wheel on top of one of the bumps then push it gently to one side. What happens to the wheel? The wheel rolls smoothly over the “road” made up of inverted catenary curves. (A catenary curve is the shape that a flexible piece of rope or chain will make when suspended loosely between two fixed supports). 