The best database I’ve found for finding peer-reviewed articles for high school students and beyond is EBSCOhost’s Academic Search Complete. I have tried all, or almost all, of the databases for researach available, and this one is better than the rest by a significant margin. The only thing it lacks is a reading-level feature, which would give the reading levels of the articles. If you are lucky enough to have this database at your school, be sure to tout it! You will be doing your students a valuable service. Although EBSCO recommends it for university students, it is also appropriate for high school students who read at grade level. A free trial is available if you want to try it out at your school.
Best Database for Finding Peer Reviewed Articles in High School