Kitna retired after the 2011 season, his 15th in the league, and was coaching this season when he heard about Tony Romo's back injury.
Kitna sent a text message Tuesday morning to Cowboys coach Jason Garrett, and the two would talk by phone for 30 minutes, he said.
"I knew the situation they were in that perhaps I could help out in an emergency," Kitna said.
"I thought it was great," said Lincoln High School football player BJ Hawthorne. "Another chance. He always taught us 'next man up' so Tony Romo goes down and another opportunity for him."
And it's another opportunity for a teachable moment by showing his students the importance of generosity. "It's not really a surprise that he's taking the money and giving it all to us because he's always just doing stuff for the school," said student Davon White.
Jamila Jones, assistant football coach at Lincoln, added: "He understands we're a school that not only needs it, but will do great things with it. We got a lot of great things going on."
It hasn't been decided where the money will go. But the school administration says it'll be something that helps all students, not just the athletes.
"It's no secret that Lincoln is a low income school and so him donating to us it really gives us hope," said Mikala Davis.
Kitna will be paid whether he plays or just stands on the sidelines, and the amount of his game check for some teachers is a year's salary.
He'll suit up Sunday as the backup to Kyle Orton if Romo can't play against the Philadelphia Eagles, in a game that will decide a playoff berth.
Kitna appeared in three games for the Cowboys in 2011 and has started 124 games overall for Seattle, Cincinnati, Detroit and Dallas.
"He's a very active guy," Garrett said Wednesday. "He's a mentally tough guy. And he's certainly very young at heart. So it was good to have him back, good to have him back in the meetings, and (I'm) excited to see him practice."
The Associated Press contributed to this report