Other writers travel with a doll or puppet from their stories as a mascot. You could develop a slide presentation that shows your writing life. Do sketches as you talk and leave a signed original for the class. Simply have the children illustrate your story as you read to them. Decide what types of programs you'll be presenting for each age group.
Some authors feel comfortable working with primary grades only.
Others want to work with middle grades or high school. I give presentations for any age group, from pre-school through adult. You can be flexible and vary programs-I try to adapt to any requests from the teachers. Or stick to your original plan, if that makes you more comfortable. Prepare short descriptions of your programs and develop a brochure.