Lesson Summary This learning experience takes three to four class periods.  The students improve the ability of their structures to support more live loads.  They share ideas for strengthening their structures.  They think about the material from which a building is constructed how it might affect the building’s strength.  They should also think about how the shape of a building might affect its strength.  They will identify the live load of a structure and correctly explain how it is affecting a structure.  The students will increase their structure’s capability to support more live load without increasing the dead load. Teacher Background The point of this lesson is for students to understand that the live load influences the stability of structures.  The students will learn that under most circumstances buildings should be as strong as needed, with the smallest dead load possible.  The greater the dead load, the more expensive the building is to build. Set-up/Management Tips In this lesson the students are given more straws and paper clips to improve their structures so they can support a greater live load.  The groups have two options: improve their existing structure or build an entirely new structure.  Remind them that their goal is to build or refashion a structure that can support the greatest live load at the highest point on their structure while keeping the dead load to a minimum.  The groups are given 50 more straws and 100 more paperclips.  Prepare the materials for each group ahead of time so they can use all of their class period for building. During this lab the students are assigned the roles of architect, contractor, structural engineer and draftsperson.  The website http://pbs.org/wgbh/buildingbig/profile/index.html features pictures and interviews of ten engineers and architects.  The roles can be assigned, selected by the student or decided by random chance.  The roles can be reassigned during the unit so that the students get a chance to experience all of the roles.  Read and discuss the roles and responsibilities with the students before starting the activity.  The role cards are on pages 99, 101, 103, 105 of the teacher’s manual.  Students should be given photocopies of these role cards.  The manual suggests posting these roles and responsibilities on a poster in the classroom.  The Group Recording Sheet for each group is on pages 91, 93, and 95 of the teacher’s manual.  These sheets outline the specific jobs the architect, structural engineer, draftsperson and contractor will complete during Learning Experience 5. The students should test their structures with the load tester after they have strengthened or rebuilt them.  After they have tested their structures have them display their structures and share the strategies they used to strengthen their structures in a whole class discussion.  Each group should be able to report the total amount of dead load, total amount of live load and the height at which their live load was placed on their structure.  Make another class group poster like the one used in Learning Experience 4 on chart paper, except add one additional column.  The poster should be given the title Learning Experiences 5 and 6 Live Load/Dead Load Challenge.  The additional column will be used in Learning Experience 6.  Each group will record their structure’s dead load, live load and the height the live load was placed on the structure.  The students will duplicate this poster and record the data in their science notebooks. Revisit and record any additions or changes the students want to make to the “Why Do Structures Stand Up?” or “Principles of Good Construction” posters. Science notebook questions and writing suggestions for this learning experience are listed below: After the class discussion about how to strengthen their structures, pages 85-86 of teacher’s manual lists questions to have them respond to in their notebooks. After the students have improved, tested and presented their structures, have them respond to questions in their notebooks listed on pages 88-89 of the teacher’s manual. Literacy Support Scientific Vocabulary The following words are key vocabulary words that will be introduced in this lesson and reinforced throughout the unit: architect draftsperson contractor structural engineer