Professor Francis Fox Piven is a communist and strong Obama supporter.
The chanting is a mind control technique to force the crowd to cognate the propaganda expressed. By repeating what is said, the kids have to pay attention. This forces their minds not to wander from deep psychological indoctrination.
In the first you link to, you see how pleased she is that the cause of fomenting revolution is underway.
From Wikipedia:
Democratic Socialists of (DSA) is a social-democratic organization in the United States and the U.S. affiliate of the Socialist International, an international federation of social-democratic and labor political parties and organizations.
DSA was formed in 1982 by ... a coalition of writers and intellectuals with roots in both the New Left movements of the 1960s and the former members of socialist and communist parties of the Old Left.
They have to pay attention to what is said and if they disagree a bit, it doesn't matter since their brain is making them say it. If they say it, they will believe it.