A simple example comes from recycling a Christmas tree. The tinsel, a manufactured decorative technology, is very inexpensive. Removing it from a tree you are disposing, makes little economic sense, but it makes good ecologic sense. If you cut the tree in pieces and allow it to decompose back into the soil, you don't want metal foil polluting that same soil. If the tree goes to a dump or landfill, one could make the argument that there is so much metal and plastic there already that your time could be better spent elsewhere, but it does not invalidate the question of what are the costs and benefits.
Activity Conduct the Cost Bubbles activity.
Conduct the PMI Chart activity. Sharing Allow presentation to the class of one or more of the work products from the activities.