Lesson Summary In this learning experience students are challenged to use what they know about the strength of trusses, as well as their knowledge of tension, compression and materials to design and build a bridge that meets requirements of load while adhering to specific restrictions.  Teacher Background In this learning experience students are challenged to use what they know about the strength of trusses, as well as their knowledge of tension, compression and materials to design and build a bridge that meets requirements of load while adhering to specific restrictions.  Set-up/Management Tips Prepare the following  materials: 3’ string, 150 paper clips, 50 straws, 30 washers, 15 3” x 5” index cards, 1 measuring tape for each group and 1 pair of scissors for each group) ahead of time.  This allows the students to use the class time for building instead of counting materials. This is the first time the students have built a structure over an open span.  Each group of four students will need to build its bridge to span a distance of fifty centimeters (twenty inches).  The bridge supports can be movable desks, books or blocks of wood.  Measure and use tape to mark the span space ahead of time so the students can use their time to build.  Locate a storage place for their bridges ahead of time. The students will need time to explore and solve problems with their structures in this learning experience (teacher’s manual page 194). Make copies of the following page of the teacher’s manual: Group Recording Sheet A Building Bridges page 201, Group Recording Sheet A Building Bridges Page 2 page 203, Group Recording Sheet B Building Bridges Roles page 205, Group Recording Sheet B Building Bridges-Roles Page 2 page 207. Optional Home-School Worksheet Building Bridges page 209 of the teacher’s manual. Optional book, not included in the kit, Bridges (A True Book) by Elaine Landau for pictures of bridges to begin the learning experience.  Read and discuss the different type of bridges mentioned in the book.  Have the students point out the shapes, columns, beams, triangles, and triangular trusses they observe in the bridges. Science notebook questions and writing suggestions for this learning experience are listed below: At the beginning of the learning experience have the students read other bridge books listed in the Teacher Resources section of the manual.  In their science notebooks have the students record four to five sentences to sum up their reactions to the books.  Have the students discuss their books and share their reactions with the class.  Literacy Support Scientific Vocabulary No new vocabulary words introduced in this learning experience.