Design icons - things that designers like and use as exemplars/references/inspiration - are part of design culture. I've been trying to think of some, and structure them into Individual/Group/Society/Global categories. There are quite a lot at the Individual level, not so many (I can think of) at the Global. They could be recurring mini case studies in the course, including attempted explanations of why they are 'iconic'.
Chopsticks (and Japanese lunchbox)
Swiss Railway clock/Mondaine watch
Chairs: Thonet bentwood, Barcelona, Red/Blue, etc. etc.
London underground map
Houses: Falling Water, Robie, Farnsworth, etc. etc.
Sydney Opera House
World Wide Web
I'm sure these examples display my age and personal interests!