More than 50 pupils were sent home from school after arriving on the first day back wearing the wrong type of shoes, including trainers and flip flops.
Staff at the Djanogly City Academy, in Nottingham, pulled 100 students out of lessons just minutes after they turned up for school on 1 September.
Those not wearing plain black leather shoes were rounded up and taken to the sports hall before 56 were sent home to change.
Headteacher Dave Hooker, who started at the school last September, said: "Being appropriately dressed, whether for school or work, is a lesson that will benefit all our students throughout their lives.
"It is our duty to give them every advantage and a key part of that is understanding that personal standards are very important."
A child was sent home for wearing this type of shoe
After the 56 pupils with the worst type of shoe were sent home, the remaining 44 were given appropriate shoes to borrow from the storage cupboards before being allowed to return to lessons.
Angry parents condemned teachers for given the children their marching orders and accused them of being "ludicrous" and "petty".
Headteacher Hooker added: "It is Djanogly City Academy's responsibility to guide and support its pupils in a way that gives them the very best life chances.
"Ensuring our uniform standards are maintained is one small way in which we do this every day."
Year 10 student Jahmal Jones Robinson was sent home for wearing a pair of black Converse trainers.
The 14-year-old, from Basford, Nottingham, said: "It was the first day back and a lot of people were pulled out of class for having the wrong shoes.
"We were put in the hall. Everyone was shocked and angry because they were being sent home because of the shoes."
Jahmal's mum, Perri Jones, 33, described the situation as "ludicrous".
Jones added: "I sent my son to school in plain black leather Converse. I don't understand how they can put shoes before education.
"We were told the uniform was going to have a shake-up and that we should provide plain black shoes, which we have.
"I don't have the money to buy new school shoes because I have just spent £200 on uniform.
"They have said that my child cannot come back to school until he has new shoes and I don't know when that will be."
Another parent, who did not want to be named, said: "My son was taken out of class, because they were not black and leather. But I spent £30 on them.
"They are smart formal shoes, it is ridiculous and petty. The school should be focusing more on educating the children than messing around with uniform policy."
But mum-of-two Joanne Brooks, 36, added: "The school are entirely in the right here.
"You just cannot let pupils turn up for school wearing flip-flops or sandals. You have to make sure they take pride in their appearance."
The academy was placed in special measures in 2013 after being rated inadequate by Ofsted.
But this year, it had a 13% increase in the number of youngsters gaining the Government benchmark of five A* to C grades, including English and maths.
The school caters for 1,197-pupils aged between 11-19.
