Real rivets, the kind that were used in the construction of skyscrapers back in the early part of the 1900's were heated until they were white hot before they were hammered. That way they were soft enough to squash under the force of the pneumatic hammering tool. And, as the rivet cooled, it shrunk in length, and it's that shrinking that made for a very tight and strong joint in the I beams that were being connected with those rivets.

I kinda doubt they'd have let school kids loose with white hot steel because of all the possible ways a law suit could result.