First of all, as someone who as taught, and been taught, I can tell you absolutely (especially from the teacher point of view) that small class sizes is key. Especially in elementry schools. There are various reasons for this, and to be honest I'm simply too lazy to type them all out right now hehe :D. However, I do agree with you that 2 billion is a lot of money, but it is something that should be done. Especially in elementry schools. However, some of this money would be better spen raising teacher saleries and benifits to ensure that top quality teacher are in teh schools. Lets be honest, I bet this nation looses a while lot of it's best teacehrs to the workplace because that's where the money is.
Now don't get me wrong, I'm not against education, but you are talking about a $2billion+ proposal to lower class size, which has not been proven conclusively to have any affect on educational quality.