Nice counter examples at fixed temperature and pressure are
- freezing of a liquid
- condensation of vapour
- slow compression of a gas
- many chemical reactions: e.g., combination of hydrogen gas and oxygen gas to form liquid water in a fuel cell
These are possible because there is a net decrease in the Gibbs free energy.
The entropy of the system plus surroundings increases.
I am trying to address this by continually testing understanding of this point with online quizzes and in class "clicker" quizzes.