For this game, you need packet(s) of marshmallows and packet(s) of spaghetti.
Split the group into two or more teams. Generally between 4-8 is the ideal team size. The goal is to see which group builds the highest tower using only the items provided. The towers must be stable.
It is fun but covers many competencies i.e. team work, communication, problem solving, leadership. It allows participants to use negotiating skills and improve their general communication...they also learn the benefit of planning.