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        Paper 
        Bridges
       
      
      
      
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 Ask the students to take a sheet of paper and construct a bridge which 
        will span an 8-inch gap between desks. They should not use any materials 
        to anchor the bridge to the desks.
 
      
       When the students have achieved 
      this first step, ask them to experiment by adding small weights, one at 
      a time, to the center of the bridge. When their bridge collapses, have the 
      students try to construct an even stronger bridge, using another sheet of 
      paper.
       What shape seemed to be the 
        weakest/strongest?
 Keep a record of the trials. Ask the students to draw the shape of their 
        bridge and mark down how much weight each bridge held before collapsing. 
        In addition to having them write down "five pennies" or "three paper clips," 
        have the students measure the weights of the pennies, paper clips, or 
        whatevers, on a scale, and record the loads on the bridges. Have the students 
        draw a cross-section of their bridges, as well as a silhouette, so that 
        they will be able to look closely at which constructions were successful 
        and which were not.
 
 
 
   
 Have the students share their particularly strong or weak bridges with the 
      rest of the class. Discuss and chart the shapes which were discovered to 
      be successful. Ask the following questions:
 
 
 
 What part of the bridge seemed 
        to collapse first?
 
 Where was the bridge weakest?
 
 What would you use to make 
        the paper bridge even stronger?
 
 What do you think would happen if the desks were farther apart? Closer 
        together? Why?
 
 What do you think would happen if you could anchor the bridges to the 
        desks? Why?
 
 
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