When school finished, his head of science excused him from a subject meeting so he could dash to the Chasetown football clubrooms to belatedly join his teammates.
And that evening, he led his low-ranked football team to one of the most remarkable upsets in recent FA Cup history.
Against the professional, league one Port Vale team, the Chasetown "Scholars" - ranked five divisions below - pulled off a 1-0 win. They will meet Cardiff, ranked 138 places above them, in the next round.
Until this week, few had heard of John Branch, 23, a semi-professional footballer and newly qualified teacher at Fair Oak Business College in Rugeley, Staffordshire.
But last year he wrote for the TES Magazine: "Football has always been a priority and I would not want a job that compromised it. The challenge is to not let one thing affect the other."
By this week, a few months into his first job, he had discovered that teaching can be all-consuming. So when his teammates - plumbers, postmen and carpet fitters - had time off to meet before the game, he was still in class.
He had thought about postponing his lesson observation, which is critical to his progression, when he discovered that his team would be playing an almost unimaginable FA Cup fixture that evening. But he did not want to seem like a prima donna, so he went through with the Year 10 lesson on smoking.
"I don't like ducking out of commitments," he told The TES.
Afterwards Colin Rich, the assistant head who observed his lesson, told him that he could have been "a little more emotive and enthusiastic to inspire the kids to work".
"I think part of that was because I was a little tired, a little stressed out, and I was thinking about the game," Mr Branch said.
Mark Sutton, his head, said his air of distraction in the lesson observation was entirely understandable: "We can forgive him for that."
That night, he captained the team to victory, while Lee Evans, a PE teacher and Chasetown goalkeeper, kept Port Vale scoreless.
After the victory, the players enjoyed a few beers. But next morning Mr Branch was back at school for the staff meeting - that and high fives from pupils in the playground.