Minnesota Transportation YOU Builds Marshmallow Bridges

Minnesota 1WTS Minnesota’s Transportation YOU program partnered with Blaine High School’s Center for Engineering, Mathematics, and Science (CEMS) to create a mentorship program. Students and mentors meet monthly and follow a curriculum prepared by WTS members. Through the program, WTS mentors aim to spark an interest in the girls in all modes of transportation. One of the most popular activities the Minnesota Transportation YOU program held was a marshmallow bridge building event. This exercise gave the girls hands-on experience in the planning, designing, and constructing phases of building bridges. These future engineers not only had fun, but also created a load-bearing bridge made of marshmallows and toothpicks while bonding with their mentors! For instructions to build your own marshmallow bridge, see below!

Marshmallow and Toothpick Bridge

The only supplies needed are toothpicks, a variety of marshmallows, and of course an imagination!marsh pic 1

Building a bridge with toothpicks and mini marshmallows is easier than using glue, although it won’t support quite as much weight. The basic building blocks will be tetrahedrons, as shown on the right. The structures will be made from many of these, joined together.

marsh pic 3Here is a beam made by joining several tetrahedrons together. Notice that adjoining tetrahedrons share marshmallows; this isn’t strictly necessary, as pieces can be attached together by running pieces of toothpicks between adjacent marshmallows.

Several smaller structures can be joined with short lengths of toothpicks rather than sharing marshmallows between adjacent pieces.marsh pic 4

A book can be balanced on four of the individual tetrahedron pieces to demonstrate how strong the construction is. Fresh marshmallows tend to let the toothpicks slide too much, so the strength of an actual structure shouldn’t be tested using weight until the marshmallow bridge has been allowed to sit for a few days to let the marshmallows get hard. Have fun!


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