Parents, pupils and staff from a threatened Grimsby school will tackle education officials at a public meeting in the town on Wednesday night.
Campaigners say pupils will be forced to travel further to school
It is the first of three meetings looking into plans by North East Lincolnshire Council to cut thousands of surplus secondary school places.
One proposal is to close Whitgift School on Grimsby's Willows estate.
Campaigners who want the school to stay open say its closure would mean pupils having to travel further to school.
A second option being considered by North East Lincolnshire Council involves downsizing several other schools in the area.
Both options include proposals to close St Mary's Catholic School and Matthew Humberstone Church of England School in their current form and open a new joint church school at Chatsworth Place, Cleethorpes.
The council predicts that if nothing is done, there could be 34% surplus places in the area's secondary schools by 2016.
Government regulations say there should be a surplus of no more than 10% within an authority's schools.
Tony Brumfield, North East Lincolnshire Council's principal education officer for sites and buildings, said: "We do accept a disadvantage of the option to close Whitgift would be the requirement of further travel by pupils.
"The difficulty when a school closure is being proposed is that you are proposing to close a school with a defined catchment area. In that case, we would have to refine catchment areas.
"In the future we think there will be less of an emphasis on geographical catchment areas as we think people will choose schools based on preference for a particular specialist status.
"We are genuinely saying we want to hear people's alternative proposals."
The council has promised that any pupil who has to travel more than three miles as a result of school reorganisation will be offered free travel.
One parent, Paul Vessey, told BBC Radio Humberside: "Once you close a school, even if later on down the line you find you have made a mistake, you cannot re-open the school.
"I would ask them to reconsider because I don't believe they are following government guidelines closely enough."