Before students can write, they need to come up with ideas about what to write. This is not a skill that comes naturally to all third graders, but mini-lessons can help them practice. One approach is to create a grid of nine squares with a letter of the alphabet or a category (like "Family," "Friends" or "Food") in each one. Give students a chance to discuss the categories with their friends and jot down ideas that arise about topics they could write about in each category.
A mini-lesson centered on describing a person can help students develop their descriptive writing skills. The more concrete you can make the assignment, the easier a time students will have with it. One approach is to put students in pairs and have them spend ten minutes describing each other in writing. Another is to have each student describe you. Guide students to pay attention to expressing specific details as they think about their subject's physical appearance, personality and actions.
A fun way to let kids stretch and express their imaginations is to have a mini-lesson in which they make up their own stories. To give some focus to the assignment, pick a particular "What If?" scenario for students to write about, such as "What if I had wings?" or "What if I were a pirate?" You may want to divide this into a series of mini-lessons that will take students through the process of brainstorming ideas, drafting, editing and publishing.
Editing is an important part of the writing process that you can use mini-lessons to ease your students into. One way is to go on a "sentence hunt" in which students look at an earlier piece of their own writing in search for one sentence they could add, change or delete in order to make the writing better. Define things that can improve writing, such as specificity, accuracy or unity of subject. Students can also spend time helping each other edit or finding fixes with you.