It would be interesting to see detailed attendance figures for the students.
I taught Algebra 1 in a school where darn near every student came to my class every day. A good half of those students didn’t miss more than one or two days all year.
I also taught Algebra 1 in a school where the average student attended class maybe three days a week. Some students only attended once a month, on bus pass day (if you’re in school on that day, you get a free monthly bus pass, good anywhere in the city). And I won’t even talk about the disruptive students.
Guess which school scored higher on standardized algebra exams.
Your experience shows what Baltimore schools’ real problem is. Oddly omitted in the article.