Mr nicely often begins his lectures by presenting students with two ideas that apparently conflict. He feels this method of presenting a paradox arouses students interest. From piagets point of view the teacher is making use of his students natural response to

Disequilibrium

Explanation:

People will naturally turn their attention to the things that we consider as an anomaly. In the present of anomaly, our brain has the tendency to focus and analyze until we understand the cause or potential effect of that anomaly. This is what often referred to as natural response to disequilibrium.

When mr. Nicely begin his lectures with conflicted ideas, it presented a state of anomaly in the students' mind.   the students' mind become more likely to pay attention to the lecture as an effort to understand what's causing the conflict in order to resolve the anomaly.