Check out this simple and student-friendly rubric which is meant to be used to evaluate student science journals. The rubric is broken into four categories, of which students can score between a 1 and a 4. Each score for each section includes explicit description of what you need to obtain that score. A guide on the bottom shows how to calculate up to a percentage grade. This is meant to be provided to the students, so they know what is expected of them with the journals, and then used to grade at the end of the quarter, or semester, or year. Sections included cover topics of Organization, accuracy, elements, and illustrations. Best wishes! Be sure to also check out my other rubrics as well!