When the Office for Standards in Education visited Endeavour school on Monday, nine pupils began a week at a local college on a vocational course, and four teachers from other schools, including nearby Kingswood high, taught Year 11 pupils, according to parents.
Paula Dorkin, whose daughter Natasha, 15, is taking her GCSEs, said:
"Inspectors won't get a fair view of the school. For the Year 11 pupils it's too little too late. Luckily, my daughter has got a good head on her shoulders. I feel sorry for those who haven't."
Phil Edwards, whose daughter Alix is in Year 11, said: "It looks as if the teachers were brought in just for the inspection."
One teacher at the school, who wished to remain anonymous, said: "The Ofsted report should be an honest snapshot of how the school is doing. What they've tried to do is dishonest and underhand."
Another teacher, who also wished to remain anonymous, added: "What the school has attempted to do is out of order. It's a poor example to set its pupils."
Kevin Beaton, head of Kingswood, is leading a team that took over running the school after David Throp resigned as head on February 12.
Mr Beaton said: "We could have sent 12 kids to Hull college, so if it was a case of getting rid of as many children as we could we wouldn't have only sent nine. If I'd been here since September I would have run this vocational course since then. There are 1,200 kids in this school. Is it really going to make that much difference sending out nine?"
Endeavour's chair of governors, Daren Hale, also played down the incident:
"This isn't to hoodwink Ofsted, they're aware of what's happening.
"We've brought in the Kingswood teachers to ensure that Year 11 pupils get a better standard of teacher than they would if we got any Tom, Dick or Harry off the supply list. If I was a parent of those children I'd be applauding the school for trying to put more experienced teachers in front of their kids."
Last month parents called for the school to be put into special measures because of lost coursework, an excessive number of teachers on the graduate training programme, and one teacher, who is no longer at the school, allowing pupils to cheat in a mock exam.
An Ofsted spokeswoman said: "Inspectors will seek the views of parents and pupils. This will enable any concerns about new teachers being brought in and the removal of pupils to be brought to the attention of the team."