Doing assignments for your child won't help him understand and use information. And it won't help him become confident in his own abilities. It can be hard for parents to let children work through problems alone and learn from their mistakes. It's also hard to know where to draw the line between supporting and doing.
Different teachers have different ideas about the best way for parents to provide guidance.
If you understand something about the style of learning that suits your child, it will be easier for you to help her. If you've never thought about this style, observe your child. See if he works better alone or with someone else. If your child gets more done when working with someone else, he may want to complete some assignments with a brother or sister or a classmate. If so, drawing a picture or a chart may help with some assignments.