CHICAGO (CBS) — With 10 signs welcoming you, it’s hard to miss Sullivan House High School on the South Side, but apparently miss school is what almost all of the students do.

Get this: 98 percent of students at the charter school are absent nine or more times a year, also known as chronically truant; yet Sullivan House High School is rated 1+, the highest mark possible in the Chicago Public Schools quality ratings.

CPS officials said chronic truancy isn’t part of their calculations. They focus more on academic growth, which is a source of pride for the principal at Sullivan House, an alternative school for at-risk students and high-school dropouts.

Student Marcus O’Daniel said he was “kind of experimenting from school to school” before enrolling at Sullivan House.

On group discussion day at Sullivan House, he is eager to chime in alongside his new classmates.

“It’s at your own pace that you learn, and I love it. This is what I’ve been looking for for a long time,” he said.

Glowing reviews, a different curriculum and test score growth are why principal Thomas Gattuso thinks Sullivan House receives the highest quality mark possible from CPS.

“You really have to work hard to be a 1+” he said. “I think part of the 1+ rating is the fact that the kids see what we try to do for them, as well as what we think they can add to our school.”

But Gattuso isn’t shy about what’s missing.

“Whether it’s work, whether it’s childcare issues, some of them have court issues,” he said.

Sullivan House is one of the CPS schools struggling most with chronic truancy, as 98 percent of students rack up nine or more unexcused absences.

Asked how a 1+ school can afford so many repeated absences, CPS officials said chronic truancy isn’t part of their calculation.

Chicago Teachers Union Education Policy Analyst Sarah Rothschild said “it doesn’t make much sense.”

CTU questions the district’s whole ratings system, calling it a “marketing scheme” for parents.

“If they’re given false information about the quality of the school, and the services being provided, I don’t know, what does that say about the diploma the children are getting?” Rothschild said.

Teachers at Sullivan House are trying to break the chronic truancy trend.

“We have kids that haven’t been in school for two or three years. So the fact that we may get a student in that misses seven days, I’m happy with that compared to where they were when they came in,” Gattuso said.

CPS also said schools shouldn’t be punished for high truancy rates, because repeat absences are often due to something going on at home.

For his part, O’Daniel said “I don’t really know why they want to miss off on this experience.”

“Overall, the experience so far, I’m loving it,” he added.

Lauren Victory