One of the most useful ways to teach students to write proper sentences is to teach students how to take apart proper sentences. This gives students an opportunity to read and work with well-written sentences and to become familiar with how they are created. Simple diagramming can be done by having students locate and underline or circle parts of speech in different colors. For example, students might go through a series of sentences underlining all of the nouns in red, verbs in blue, adjectives in green, adverbs in orange, pronouns in yellow and conjunctions in purple. After that, students might draw a line between the words that separate the subject from the predicate. Once students have finished studying a series of sentences they can look for patterns in the way sentences are put together.
Similarly, students can study properly written sentences by trying to reassemble them from their disassembled pieces. Start simple by choosing a well-known sentence or phrase and write each word on a separate card. Give each student a stack of words and encourage them to try and reassemble the words to create a sentence. On the back of each card, students can write what part of speech they think the word is. Encourage students who come up with different answers to share their thinking and to decide if the sentence they created has all of the hallmarks of a proper sentence.
Students who are unable to create their own proper sentences often are able to identify sentences which are not properly written. Proofreading activities sharpen fourth-graders' writing skills while helping them become more aware of what good writing looks like and sounds like. Provide students with proofreading activities and encourage them to find errors and explain what makes them errors. Becoming confident with the language of grammar also builds students' confidence with grammar itself.
Revise and revise again. Simply pointing out to students where they have made mistakes and what those mistakes are helps students identify where they are struggling in their own writing. Give students very specific feedback on their writing. Ask students to explain to you why one of his sentences needs to be corrected and then guide him in choosing the correct way to fix it. Encourage students to celebrate their success by sharing polished writing pieces with their parents and peers.