Not to over share anything, but the one time I skipped a day with my parents permission, because they noticed I wasn't feeling too hot. I had a major panic attack in the car on the way to school the next day, worrying about my absences count and my grades.
THIS WAS IN HIGHSCHOOL
Parents, teachers,etc., PLEASE, take in account that growing children are not robots. They can't just be reset or optimized if they are not working to YOUR standards. They are living, breathing gremlins, who like all living organisms, need rest and food.
When I was a kid I had a reputation for faking sick because nothing much seemed to be wrong with me. Years later I found out my symptoms were psychosomatic due to the constant stress of untreated mental health issues. I spent 20 years in chronic pain because the adults around me just saw a child who didn't want to be in class
Listen to your goddamn kids.