Two UW-Madison researchers have spent 20 years studying how 9/11 is taught in schools. Here’s what they learned.

As the World Trade Center towers collapsed, Diana Hess wondered if she should cancel class.

It was Sept. 11, 2001.

Hess, then an assistant professor in the University of Wisconsin-Madison’s School of Education, started hearing whispers that the entire campus would shut down. She had been preparing for an evening class for social studies student teachers, who were working in area middle schools and high schools.

But now, the world was changing before her eyes — and so was the social studies curriculum.