STEP THREE: CONSTRUCTION
This is the meat and potatoes of STEM. This is the construction phase. Students now build their structure using the materials that they purchased and the ideas that they feel will work. As they are building their structure, they are revising it from the feedback they are getting as they are testing the structure. For example, they may start out building their catapult one day, decide it will definitely not work as is, and rebuild it completely a new way. They can "return" undamaged supplies to the store to add that money to their "account".