Ideally, students learn better in a standards-based environment because everybody's working towards the same goal.
Teachers know what the standards are and choose classroom activities that enable students to achieve the standards.
Students know the standards, too, and can see scoring guides that embody them. The students can use them to complete their work.
Parents know them and can help students by seeing that their homework aligns with the standards.
Administrators know what is necessary to attain the standards and apportion resources and buy materials to ensure that students are able to reach the prescribed standards. Schools communicate the standards to parents via newsletters, etc.