Low grades can mean more than just having trouble grasping the material...They can indicate indicate deeper issues.
If your child is having low or failing grades, the best response is to simply schedule extra help or tutoring. However, there can be other causes that are sometimes overlooked.
Under Stimulation
If the material is too easy for your child, then he/she wont even put in the little effort needed to get it done at all.
Depression
Low grades can be a result of emotional issues. Kids aren't going to care much about grades if they are depressed.
Social Issues
Shyness and social anxiety can also affect grades. Fear of reaching out for help, or engaging in group participation can obstruct a child from progressing academically.
Summary
Failing grades may result in having to go to summer school, being left back, and dropping out. These consequences can have devastating effects on a child's development.
Most of the time low and failing grades are the result of lack of effort. But there are many different causes for that lack of effort. Rarely does a student fail a course when they are putting in a strong and honest effort. If the class is just too hard, then extra help and tutoring can fix that.
But if your child is generally failing many classes, this can indicate that they just don't care about doing well in them. This may represent deeper emotional or social issues, which is a bigger problem than just bad grades. If your child doesn't respond to tutoring, please schedule an evaluation with a therapist. (Click here for my recommendations)