CLARKSVILLE, Tenn. -- Schools across the state have begun the process of nationalizing their standards. Now students will have to work harder for good grades.

Some parents worry the change will hurt their kids' chances of college acceptance.

Clarksville and Montgomery County students are making the most of their summer, many of them with no idea what lies ahead.

It's going to be more of a challenge, because schools across the state are changing their standards. Students will now face a harder curriculum, new assessment exams and more graduation requirements.

The goal is to make students more competitive.

"This is probably the biggest thing I think that's happened in Tennessee schools in my lifetime," said Michael Harris, director of the Clarksville-Montgomery County School System.

But the change won't come easy. Even teachers have to learn new material. They are already hard at work in the classroom this summer, participating in more than 500 training sessions.

"It's going to be tough, because it is a higher level of learning," said Lisa Courson, a fifth-grade teacher at West Creek Elementary School.

Educators said students' grades decreasing is a risk they're willing to take.

"I'd rather know that our students are getting a more rigorous environment in their learning and not worry so much about the grades," Harris said.

Some parents are still worried about grades.

"If their grades start going down, that's not going to look good at the very end when they're graduating from high school," said one parent.