PHOENIX — Students now in eighth grade would get free tuition a state colleges and universities if they maintain a B averag under a proposal Monday by Gov. Janet Napolitano.

 The governor, giving her sixth State of the State address, acknowledged the state’s current budget deficit. And she said the shortfall in tax revenues prevents her from proposing extensive new programs at this time.

 “But we can look to the future,’’ she told the Legislature.

 Napolitano said lawmakers should “make a contract’’ with the Class of 2012 — and those beyond — that if the maintain good grades they will not have to pay tuition at a public college or university.

 Students also would have to “stay out of trouble,’’ which the governor’s office said means not using alcohol or drugs or engaging in any other illegal activity. And they would need to perform 100 hours of community service to qualify.

 Napolitano’s proposal is actually an eased version of what already exists.

 The state Board of Regents already offers free tuition to graduating seniors who maintain a 3.5 grade point average — essentially half-way between an A and a B. And they cannot do i all with easy electives: They must have at least a B or better in all their required courses.

 On top of that, there is a requirement that students score at the “exceeding standards’’ level on the math, reading and writing parts of the AIMS tests which already are required to graduate.

 Last year 2,469 students qualified for the scholarships.

 State School Superintendent Tom Horne said the existing program, with its requirement to make good grades on the statewide test makes more sense than what Napolitano proposes.

 “If you do it by the subjective measure of teachers giving kids Bs it’ll put unbearable pressure on the teachers to give Bs to everybody,’’ he said. Horne said that would just lead to mor “grade inflation.’’

 Napolitano did not have a price tag for what her plan eventually would cost.

 Even before 2012, Napolitano wants some help for students at the state’s three universities. She wants incoming freshmen to have a guaranteed tuition for their entire four years.

 At this point, only Northern Arizona University will be offerin that to students. Arizona State University is proposing a cap on year-over-year increases; University of Arizona President Robert

 Shelton rejected the idea last year when the Board of Regents set tuition for next year.

 Napolitano also renewed her request from last year that lawmakers require that students stay in high school until they graduate o turn 18; now students can leave at 16.

 But House Speaker Jim Weiers said forcing students at that age to stay in school just won’t work.

 “I don’t think that you can bring a kid to class and make them learn any quicker than you can bring a horse to water and make them drink,’’ he said. “All you’re doing is creating an environment for the rest of the kids that want to be there that’s not going to be conducive to learning.’’ Senate President Tim Bee said it would be more productive to figure out why students are not completing their education.