There are some great thinkers in Ms. O'Toole's Kindergarten class at Gretna Green School. The goal was to go through the basic engineering design process to build a bridge made from marshmallows and toothpicks. They started with a drawing (design) and used their knowledge of shapes to build the base of the bridge and test it out.  It didn't hold up so well in the testing phase so they built strong triangle sides which provided a lot more support.