How about a normal backpack for school? You know, something without molle that doesn't scream tactical or bring unwanted attention to yourself?
In which case... The North Face Recon.
http://www.thenorthface.com/catalog/...r/recon_3.html
It has features specific to your application. And is typical TNF quality.
As a further aside, most MEC (mec.ca) packs will be of MUCH higher quality than any asian knockoff tactical shit. And they have a kickass return policy/warranty, perfect for the cash strapped student who can only afford to buy once. Go there.