Stewart McGough has spent part of his Easter holiday teaching maths revision classes for the past three years.
The 41-year-old, from Kettlethorpe high school, in Wakefield, works two days at a supply rate of pound;130 a day.
He said: "It is actually quite enjoyable coming in during the break. There is a more informal atmosphere in the school. You know the kids want to be there. You also get to work with pupils you wouldn't normally work with, which makes a nice change."
He said the take-up had been less than in previous years, with about 150 pupils coming in (60 per cent of the year group).
"Form teachers ring around to try to get the pupils in, but for me the good part of it is that you are teaching kids who have opted into it. You don't really want to be going around saying, 'You must come in'. There is a culture in the school of offering extra revision classes, but it hasn't interrupted my holiday too much. I chose to work the two days, and if I had wanted to I could have opted for one. We're used to the extra work in maths because we offer booster classes for key stage 3.
"The extra money comes in useful, too. The rate we are paid is for teaching five classes, but the day ends at 2.20pm. I feel like I've earned the money: I put a fair bit of work into the lesson plans."