On Friday, Vallas appeared on Good Day Chicago where he said he believes children should be back in the classroom.
Vallas said it has had a negative impact on students socially, emotionally and said there's been an increase in violence.
He also had a message for Lightfoot.
"The previous CEO said the same thing. She needs to hang tough. In other words, if the teachers do not come to work, they should not be paid, period. That's number one." Vallas said. "Number two, she needs to void the contract. They gave the union the richest contract in history - $1.5 billion. It's the richest contract in history. They should void the contract."
"The third thing is they should lift the cap on charters because if there are charter schools that are willing to stay open, parents should have the option and the union forced the district to cap charter school enrollment. And the fourth thing is they should take that tax increment financing windfall that they give to the district every year and they should use that to provide tuition support for parents who send their kids or want to send their kids to parochial or private schools."
Vallas was CEO of Chicago Public Schools from 1995 until 2001.