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8th Grade Physical Science: The Last Straw

Tuesday, October 4, 2016

In a recent physical science project to investigate forces of tension and compression, eighth grade students were challenged to design and build a bridge from drinking straws, straight pins, masking tape, and string. The bridges needed to span a 45cm gap between two lab tables and support at least a baseball, maximizing carrying capacity while minimizing material cost.

The research phase of this project included watching and reading selections from Building Big: Bridges by David Macaulay, using an online interactive lab to learn about forces at play in various bridges, and testing different types of bracing using coffee stir sticks and binder clips to stabilize a shaky wall made of popsicle sticks. Students applied their findings to design and built a bridge in small, cooperative groups.

As a whole class, they identified what constituted “bridge failure” and created a standardized method for testing bridge strength. Following the excitement of pushing their models to their limits - some supporting 15+ bocce balls - they wrote individual reports detailing how and why the bridges failed and identifying improvements for Version 2.0.