Good grades and high test scores still matter â?? a lot â?? to many colleges as they award financial aid. But with low-income students projected to make up an ever-larger share of the college-bound population in coming years, some schools are re-examining whether that aid, typically known as merit aid, is the most effective use of precious institutional dollars. George Washington University in Washington, D.C., for example, said last week that it would cut the value of its average merit scholarships by about one-third and pare the number of recipients, pouring the savings, about $2.5 million, into need-based aid.