Pupils at Manchester King David High School will have to attend classes on the royal wedding bank holiday.
Instead of having the day off, pupils will be celebrating April 29 in school uniform behind their desks while most other schoolchildren in the country are enjoying an extra day off.
Chairman of governors Joshua Rowe said the school would be opening "out of desperation" because the combination of Jewish holidays and Easter weekend just days before the wedding are causing havoc to GCSE and A-Level studies. It is compounded by problems with the legal number of teaching days the school must remain open.
Mr Rowe said: "The school is due to be shut for two weeks for Pesach and the Easter weekend. We re-open a day before the wedding. If we closed the school for the wedding we couldn't open for one day. Students would then be off for almost three weeks.
"It already leaves only two days to catch up for GCSE and A-level students, whose exams start almost immediately in May. They can't be off school for three weeks."
Mr Rowe said staff were consulted about starting the Pesach school holiday a day late to compensate for the wedding bank holiday. But this was rejected by teachers who said they would not have enough time to prepare for the Jewish festival, or had already booked holidays abroad. The extra day will now be added to the summer holidays.
But Mr Rowe had words of comfort for both teachers and pupils. "We certainly won't be ignoring the royal wedding. There will be a big screen and we will lay on a special lunch for the children. "The message to kids is, we will be celebrating the royal wedding - at school."