Long balloon fills because of Bernoulli effect

A very long bag (initially open at both ends, then tied on one, making it a large balloon) is spread out flat on the lectern. Without kinking the professor blows air into the balloon with it directly wrapped around their mouth. The process is slow and laborious. Then, again without kinking the balloon, the bag is held about six inches from the professor’s mouth, and the professor again blows into the bag. The high velocity of the professor’s breath causes additional air to the pulled in from the room and the long balloon fills rapidly.