I think the answer to this varies student to student and it is something you kind of have to judge based on the student and family. For younger students, it may be best to address your concerns through a parent-teacher conference. Show data that supports your concerns, and work with the parents to come up with solutions. With older students, it may make more sense to talk to the student first, but make sure this is done in private and in a way that will not make the student feel discouraged or like a failure. Of course, you can always reach out to teammates and staff that may have more experience and can help guide you on what to do in specific situations.

I believe its always good to be direct with the student. No matter the age, I think talking with the child privately is always best. If things don't get better, having a parent/teacher conference is the next step. When you first start noticing a trend of failing grades, I would start making copies of those assignments for when/if you have to talk to the parents. Most parents, by nature, are protective of their children so they may be resistant to your claims. However, having a sit down with them and showing them the trend of failing assignments is what will open their minds. If you have a student on level, I would use one of those (blocked out name) to show where the child should be at in that point of the year. This will give the parents a reference point and where to help in the areas of deficiency. You could work together to find homework assignments or apps that they parents could support the child with. If the grades do not improve, I would go to the school counselor and VP to suggest possible summer school or retention.