Determine which geometric shape provides the most stability and strength.
Groups of 2 students
Materials: 7 straws, 14 paper clips or toothpicks and soaked white beans
Brainstorm: Adjectives to describe the straw
Ask: How does the straw bend? How useful do you think straws are as building materials? How might the straw's qualities change depending on how they are used?
Demonstrate how to connect the straws and paper clips to form a regular rectangle and a triangle. Push a paper clip into an end of the straw. Attach another paper clip to the one in the straw and push another straw on the paper clip. Complete this process until you have the desired geometric shape. Position shape in a manner where pressure is applied to an endpoint, for the test. Now press the endpoint down slowly. What do you notice? Which members are in tension and which are in compression? What does this information tell you?