A fall in the number of children starting primary school in Kent means schools may have to shut or amalgamate, the county council has warned.
Ripple School near Dover stayed open despite having just 35 pupils
When the deadline for applications passed, 3,000 places were unfilled - equivalent to about 15 primary schools lying empty in the county.
Kent County Council said it was a result of a falling birth rate.
It said it would look at combining some schools with one head responsible for two or three sites.
Councillor Leyland Ridings, cabinet member for schools organisation, said the authority was looking at several methods of handling the drop in pupil numbers.
And he said the building of thousands of new homes in the Ashford and Thames Gateway areas would mean it was likely extra schools would soon be needed there.
He said: "We have many different proposals which we are looking at, at the moment, for how to deal with this.
"For example, a foundation of schools, with maybe one head teacher and a group of governors to look after two or three schools.
"Because schools are funded in effect on a pupil by pupil basis, if you've got a class of 27 to 30 then that's an extremely viable class.
"If it comes down much below 25 then that's a completely different situation and you just don't even cover the teaching costs."
Mr Ridings said in areas where schools were shut or partially closed attempts would be made to make use of the buildings.
He said some could be used as children's centres, of which the county was expected to have 102 by 2010, or as community centres.
In September 2004, a lengthy battle to keep open a primary school with only 35 pupils - Ripple Primary near Dover - was won, despite the county council warning it was not financially viable.