Decide what you feel are the necessary elements for a great thesis statement. Good thesis statements should state the topic of the paper with careful emphasis on the particular focus the student will have about this topic. It should also include an overview of the supporting points that will be covered in the rest of the paper. Thesis statements also need to use active verbs that grab the readers attention and are error free.
Create a rubric that grades each element of the thesis that you have deemed necessary. This rubric can give students a 1 to 5 rating for each element that will help determine the overall grade. If students earn a total of 25 points for 5 categories, that means they have earned an "A" or 100 on their thesis statement.
Give the students a mock rubric like you will be using when you grade their assignment. The rubric can be in a form of a checklist that students can check off before they turn in their thesis statement to ensure that they have included everything they need in order to be successful.
Use the rubric to grade each thesis statement thoroughly. A rubric allows you to grade a lot of thesis statements in an objective manner since you are looking for certain elements and then checking off that students have each of those. You are also grading the quality by grading them on, for example, a 1 to 5 scale with 5 being the best and 1 being the wost. You could also use a holistic rubric that grades the overall thesis statement for quality.