For this unique construction project, you'll need to gather a bag of large marshmallows, sturdy plastic straws (note: bendy straws do not work well for this activity), a clean work surface or a large piece of butcher paper to work on.
Before the children begin creating for themselves, demonstrate how to insert a straw into a marshmallow and then begin to create your sample structure.
Challenge the children to think of what they would like to build with their materials. Discuss how planning ahead is an important part of the engineering process.
Distribute the marshmallows and straws and have the children begin working to create the structures that they've planned.
Once the children have completed their structures, provide time and space for them to analyze their structures and come up with ideas for improvements and changes.