Dr. Love began the class by giving the students legos. The students then had to try combining the legos in various ways in order to develop a hypothesis about what makes structures balance. This allowed students to complete a fun activity to practice the scientific method. The students then used the Cross Beam Applet to discover a more complex hypothesis about the balance point of a structure.
After the break, Dr. Love led a discussion on compression and tension, focusing on how trusses are in tension or compression when used in constructing bridges. The class then looked at the Bridge Design. The applet allows the students to build a truss, understand how the forces balance, and visualize the compression or tension of different parts of the truss.
In the afternoon the students got the opportunity to experiment with these forces (tension and compression) on their own. After learning how to use one of Shodor's modeling applets, the Bridge Designer, to build their own structures on the computer and see how these forces affected them, the students were challenged to build a bridge that could hold 100 pounds of downward pressure and 20 pounds of pressure to the right. Then the class competed to see who could build their structure so that they had the lowest maximum amount of stress on any individual truss. There was a lot of variation between the different structures that the students came up with, and everyone really enjoyed seeing what others made and trying to improve their own.
After modeling building a structure on the computer, the students were then challenged to apply the skills they had learned to try to support the largest number of marbles as high as possible in the air using only straws and pins to support the two cups of marbles. All of the structures were unique, but all of the groups succeeded in holding both cups all the way full of marbles.