Dr. difonzo notices several students nodding in agreement as he lectures. subsequently, his rhetoric becomes more confident and more passionate. the students have provided reinforcement.

I think the students have provided : Positive reinforcement

By nodding during his lectures, Dr. Difonso will get the perception that students pay attention to what he's talking about.
By getting this, Dr. Difonso will fell more valued and validated by his students, and this will lead to more passion for his works.

Was giving by lincoln on march 4, 1865-as lincoln prepared to speak, the civil war was drawing to a close-lincolns address of 703 words was the second shortest inaugural address-lincoln mentions god 14 times-505 of the words were one syllable -he used the word "war" or it's pronoun 9 times