Project-based learning looks promising to teach principles classes. For example, look at this possibility (Peter Anthony) for micro:
The scenario is based on a government decision to impose a price ceiling on gasoline. The Project is aptly title “The Invisibe Hand.” Students are members of a policy group. After listening to voice mails from a variety of stakeholders concerned about shortages and reading an editorial from a oil producer they are tasked to set priorities as to who should receive gasoline, set the price, explain how a price ceiling will lead to shortages and black markets and write their own editorial. . .
See also from previous posts: teaching economic principles with blogs, in the "Age of Empires," with flowcharts. Or "bring the back of the textbook to the front."