When in college, I worked at a Sigma Chi frat house on campus to earn $$.
I helped prepare the evening meal after my daily classes & then helped do the dishes afterwards.
One night as I was clearing the diningroom table, I noticed that in the parlor, the brothers were in a circle around one adult which I recognized. It was my/our Greek mythology professor.
He was tutoring them all for free (he was a Sigma Chi alumni) while prepping them for the midterm. He was giving them the answers!