AUGUSTA — A state oversight board has approved three more charter schools in Maine.

The Charter School Commission on Tuesday signed public charter school contracts for Baxter Academy for Technology and Sciences in Portland; the Fiddlehead School of Arts and Science in Gray; and the Harpswell Coastal Academy in Harpswell. The schools will open in September.

They will join the Cornville Regional Charter School and the Maine Academy of Natural Sciences, providing Maine with five different public charter schools.

Up to 10 public charter schools can be established in the state over 10 years.

Charter schools provide alternative educational models for students who might not fit into traditional public schools.