Ernie and Luke were teaching the class this morning. Ernie explains the activity and reviews what they talked about Monday which was gravity. He mentions trusses because they will be building structures with straws and the goal is to have the structure that holds the most weight. Ernie goes on with talking about forces that effect trusses and he uses the words compression, gravity, tension, nature, and weight in marbles. He uses a sponge with drawn boxes on it and squeezes it to represent how the blocks look when thereÃ¢ÂÂs compression. He then stretches to show how the blocks look when thereÃ¢ÂÂs tension.
Next he tells the kids to open the laptops and go to the website shodor.org/~ernest/eit which is a page with examples of trusses on it and a link to a truss applet to build trusses. He gives them instructions to mark dotes to make a triangle which rep. connection points to beams. They then add 50 units of weight and then they click anywhere on the grid and it shows them the calculations for tension and compression.
Ernie explains the assignment they need to build a structure that will hold the most marbles in a cup on top them. Their each going to get 50 straws and they will be in teams of two. They will also be given a pin, piece of cardboard a toothpick. Dr. Love then talks about some hints and or tips for the straws and the requirements for the challenge. The scores will be added up by two numbers multiplied, which will be the number of marbles and the height of the cup. They get roughly 55 min.