Are humans willing to accept they could?

Sometimes the days are gorgeous, balmy and calm with the sky a cloudless soft baby-blue. On such days, I am often stuck in a dark windowless auditorium, lecturing about 100 university students in my animal behaviour class. The pull of the day affects us all. I am somewhat less enthusiastic in talking about the computer-generated slides that I am showing, and the class is restless, anxious to get outside to enjoy what is left of the day.
At such times, I switch to discussion mode. I start asking the class questions that can stimulate a conversation and bring out some opinions. The students usually perk up, particularly if the subject is one that really interests them.
One of my favourite topics is