As incentives go, rewarding pupils who turn up to lessons on time with the chance to meet Michelle Obama probably takes some beating.
The head of the north London girls' secondary that put on a special concert last week for the First Lady of the US decided which pupils would attend according to their punctuality and attendance.
Jo Dibb, who has been head of Elizabeth Garrett Anderson Language College in Islington for the past three-and-a-half years, said narrowing down 1,000 pupils for the 250 places available was not as hard as it could have been.
"It was for the ones who contribute to the school," she said, adding that she hoped those pupils who weren't there took it as a cue to improve.
The Obama effect tends to get mentioned when the world economy or geopolitics is on the agenda, but its impact on the school has been enormous.
"There are 2,500 schools in London and they chose us," Ms Dibb said. "The children's self-esteem has gone through the roof."
And following Mrs Obama's speech, in which she said it was "cool" to get good grades, the Easter holiday Year 11 revision classes have seen increased numbers.
"Attendance has probably gone up as a result of her visit," Ms Dibb said. "It has been so important for our school because she is such a role model for the girls. This is something they will tell their grand-children about."
The pupils knew a special guest was coming, but some thought it could be Michael Jackson or the US rapper 50 Cent.
Brenda Mensah, 16, who high-fived the President's wife at the end of the concert, said: "She definitely is a hero. We watched her go through loads of things during the election and she's such a strong individual. It's really lifted our spirits and shows we can do better things for ourselves."
And the high-five? "I thought, 'Did she ...? No. Did we just do that?'" said Brenda.
Ms Dibb said the school knew Mrs Obama was definitely coming only two weeks in advance. Her appearance had been prompted by a visit just before Christmas from the US embassy's cultural affairs department to talk to pupils about the civil rights movement.
"They were very impressed with the children, and about five weeks ago I was contacted by the US embassy about the possibility of her coming," Ms Dibb said. "Only myself, my personal assistant and the two deputy heads knew."
She admitted it was hard to keep the news under wraps. "What do you do when all you want to do is shout it from rooftops?" she said.
Once the visit was confirmed, Ms Dibb had a series of meetings with senior figures from the counter-terrorism unit, the Metropolitan Police and the US Secret Service. Not that such people daunted her.
"If you're a head, you don't tend to listen to people talking nonsense," she said. "I know my school and we would say, 'No, that won't work. This will work instead.'"
The alternative to the school visit for Mrs Obama was a trip to a south London art gallery. "She can go to an art gallery any time," Ms Dibb said. "The effect she's had on the girls has been tremendous."