The question has been asked whether science fair judging is commensurable with report-card evaluation. The fact of the matter is that they are not. Science fair judging, by nature, is process driven and formative in nature, because it literally examines the process by which a student performs his or her science. Report-card grades, by definition, are summative. Moreover, the science fair rubric templates provided do not assess things like effort, time spent, and other less objective criteria used to assign a grade.
Usually, the grades assigned by a science fair rubric will be lower than the report-card grade. This is because a science fair rubric assesses the process of good science using an idealized standard that is not normalized for high school students. The purpose of science fair rubrics being constructed this way is that it gives students a goal to which they can aspire, and by reaching those goals, they will have a better understanding of how to perform good science.