Dedicate a notebook to this journal. By using a dedicated notebook—such as a theme book or spiral notebook—instead of loose-leaf paper, you can more easily keep track of your journal entries.

Write in informal, conversational English. Do not feel compelled to use overly elaborate vocabulary; instead record the information in your everyday tone, using words that you would commonly use when speaking to fellow students or teachers.

Make your first journal entry on the day you begin your project. Your journal should record the entire project completion process, so make your first entry as you begin your project instead of waiting until you are partially done to take up the task of journaling.

Record an explanation of why you elected to undertake this project. If you observed something that compelled you to select your project topic, discuss this observation. Avoid saying that you are doing the project as an assignment, or that you just randomly picked it because you needed a science fair project. There had to be something that made you select this project over all others.

List any thoughts or ideas that you have, even if you ultimately abandon those ideas. Your science fair journal should record all your thoughts and ideas as you complete your project, not just those that proved fruitful.

Create entries in this journal faithfully. To ensure that your journal keeping isn't spotty and irregular, commit yourself to writing an entry on a regular basis. Set up a schedule for entry writing, such as every Monday, Wednesday and Friday, or composing a new entry every other day.

Place your journal on your science fair display table so that spectators can peruse it. While some might not wish to view your journal, others delight in getting a glimpse of a young scientist's thought process.