Low quality article that ignores the issues and fails to acknowledge the reason for phones being necessary in school; likely because they're talking about a non-American school.
That said; they also didn't acknowledge that the devices can be used to enrich studies when applied and used correctly.
The study they cite in the article is low-quality data that conflates correlation with causation and relies on wildly inaccurate self-reporting from students, parents and teachers.
This isn't a controlled trial; this isn't even a blinded study; nor is the data integrity controlled...it's entirely self-collected and recorded by unqualified observers.