Parents signing off on the homework does not mean they were actually involved with the homework. It means they signed it. Homework for kids your grandkids’ age makes sense in moderation because they are essentially memorizing a lot of things. Handwriting is a physical skill that requires practice but when I look at all of the adults whose handwriting is borderline illegible, most of whom had penmanship homework, I wonder how successful the homework assignments actually were long-term.
I’m guessing the school environment and what they learn in school has much more to do with where they are educationally than going home and doing homework.
Learning cursive handwriting is no longer required in many elementary and middle schools. Don’t know about high schools.