The Concord Consortium is a research and development non-profit that aims to improve the teaching and learning of technology in pre-college classrooms. This interactive and engaging activity for elementary school students brings the nuts and bolts of engineering to life by inviting students to design, build, and test a bridge made with file folders in order to see which design is the strongest. The activity, which runs entirely in a web browser (preferred browsers include Chrome, Safari, Firefox, and Internet Explorer), meets a range of AAAS Benchmark Alignments. To participate, readers simply select Launch Activity. Along the way, they'll peruse information, answer questions, and move through the steps of building their own bridges. This interactive engineering activity is bound to spark an interest in STEM subjects with elementary school students.