In his first remarks since the planned school closures were announced, Key said changing demographics, costly repair bills and ministry research were behind sweeping proposals to close 13 schools and put 25 through some form of merger.
Speaking at the official opening of Press House today, Key said the Government "could obviously put everything back where it was".
"But just like the CBD isn't going to be put back in the way it was in the past, it won't always make sense for the schooling system to be completely replicated in what you had.''
Christchurch's demographic pattern were changing, with people are living in different parts of the city, he said.
"The demands will be different.''