The early grades are the perfect opportunity to teach good editing skills. For many writers, it is hard to go back and find mistakes. Help students to look for specific errors when editing. They can't focus on every error all at once. It could be spelling, grammar, punctuation, or another area for which you want them to edit. You have to tell them after having modeled several examples from student writing.
Here is an example. A student in fourth grade may be ready to learn how to edit for wordiness.
Consider this short writing sample:
Leslie was going to tell her mom that she got in trouble. The principal said that she was going to lose a week of recess because she stole something from the cafeteria.
This student shows some advanced sentence structure. You could point out that the sentences are excellent and could be improved by eliminating the use of the word "that. "