A St. Paul charter school that prides itself on academic rigor has proof it can walk the walk.

Nova Classical Academy, more precisely, its Upper School, is the only high school in the state to earn a perfect Multiple Measurement Rating (MMR) from the state Department of Education in 2016.

Under the MMR system, schools are measured for performance in four categories -- proficiency, growth, achievement gap reduction and graduation rates -- and given a score of 0 to 100.

Two other schools -- Jie Ming Mandarin Immersion Academy in St. Paul and Hilltop Primary School in Minnetrista -- also achieved 100 percent ratings. They are elementary schools, and received perfect marks despite not being rated in all four categories.

Eric Williams, executive director of Nova Classical Academy, said the 100 percent score is significant because it "highlights the hard work and talent of our students, the strength of our Classical curriculum, our amazing teachers and staff," and the support of parents.

Classical instruction is a teaching approach that emphasizes grammar, rhetoric and logic.

In 2015-16, Nova also drew media attention when it was pulled into the debate over transgender rights.

In March, the parents of a transgender kindergartner filed a discrimination complaint against the school claiming their child had been bullied after starting the school year as a boy and switching that identification to a girl midway through the year. The parents moved their child to another school.

The complaint, filed with the St. Paul Human Rights Department, remains open pending investigation.