Catch errors by reading aloud
One of the best ways for your child to edit her papers is by reading them aloud. When she has to take the time to decode each word, small errors that would otherwise have gone unnoticed (both by her and by spellcheck) are more likely to become apparent. Reading aloud will also help her hear the flow of her sentences and the transitions between paragraphs. She’ll be able to identify portions that may need to be clarified or reworked. Finally, it’s a good policy to make your child edit her own paper before you have a look at it: your job shouldn’t be to catch mistakes but rather to act as a sounding board for refining ideas.