This is a timely subject with school starting up. It has been my experience with all of my children that they are afraid to talk to their teachers about problems they have in school. It doesn't matter what the problem is: late homework, trouble hearing in the class, not understanding the material. They would rather die before talking with their teacher about it.
So we've had to come up with some solutions, especially because in our town, teachers take a dim view of "helicopter" parents who interfere with the teacher/child relationship.
So here is what we've done:
1. Make sure the child meets the teacher on 'back to school night' and talks with them so they are not so scary.
2. Go to conferences and tell the teacher that your child is afraid of talking with them as an authority figure. This sometimes helps them to be softer toward your child, making it less scary.
3. Don't ever interfere yourself about things like late homework. This sets a precedent, and then your child will fight ever doing it themselves.
4. Email the teacher beforehand and tell her that your child is going to talk with them, and they are really nervous about it...so the teacher can be sensitive.
5. When misunderstandings occur, help the child email the teacher and explain her real feelings. The email is less scary and threatening and sometimes the child feels more comfortable with this format of communication.
6. Keep encouraging them to talk to their teacher. The child may just need lots of pep talks, and "you can do it" speeches. That seemed to work with our oldest daughter.
7. Role Play- play the part of the teacher while your child talks to you, in order to practice.
8. If it's something really important, you will need to talk to the teacher yourself. You can determine what's important by thinking; "Is this an adult issue, or one a child can handle?"
Each child is different, but hopefully there is some advice here that may help. Good luck!