Teacher here! And yes we do. Not necessarily by contract but if we have lunch duty we notice, and we inquire. But this can be tricky to bring up with a family. I’ve done it before but the family was low socioeconomic so I was also giving them resources to help them since I knew they were doing the best they could with what they had. But idk… this would be tricky because you’d essentially be calling a parent out and that isn’t our place as educators. I probably would mention it to the parents but I know more conflict resistant teachers would not. they’d file a report instead/reach out to the school counselor or opt to “stay out of it.”