Total economic aid a year averages 30 billion bucks.
Total federal debt $18 Trillion (please don't start with the real number is higher crap)
Stopping all economic aid today would mean that in 600 years from now the debt will be paid off.
However, you are not realizing how much of that aid actually ends up benefiting the US. Many of the countries that get aid end up making progress in development, they end up buying things from American companies etc.
Every day of the week another story breaks how much the government overpaid for something. Yesterday the story was that to digitize a few PDF files using an app the government so far spent over 1 billion dollars.
http://www.westernjournalism.com/the-federal-govt-spent-1-billion-what-they-got-for-it-will-blow-your-mind/Endless examples of gov. waste that nobody seems to talk about, always on the agenda is this foreign aid BS.
As far as stopping public school funding, well much of that comes from the state not from the federal gov. and even if all came from the federal gov. what the heck kind of idea is that anyway?