Rubrics are used primarily for assessment but they are also useful tools for setting expectation standards for a task, and for providing focused feedback to students on completion of a task.
Rubrics are generally laid out in a table or grid as in the example below. Thy consist of a number of criteria (sometimes referred to as dimensions) under which the work is assessed, a grading (or rating) scale, and descriptors for describing student performance at each level for each criterion.
In the example below you can see that there are four criteria, nine levels (not counting zero) and a varying number of descriptors for each level and criterion.This example is probably the most widely used rubric for assessing student writing in the world. It is the public version for the IELTS academic writing examination Task 2 and you can access a pdf version from the ielts.org website, from the British Council or from IELTSidp.
The main rationale for using a rubric is to ensure objectivity and to improve consistency of grading between examiners. Consistency can only be achieved through training and the use of models - example essays of a range of standards. Models are also useful for students. Where possible, students should be given the rubric along with their task description and also an example (model) of a high scoring essay. In this way students can better understand what they are aiming for and how they will be evaluated.
Students also need good feedback. A scored rubric is better than a simple grade or percentage. But students need more than this. They need personalised comments and suggestions if their essays are to have any formative value. This is where good rubrics can help. They can form the basis of a discussion about the quality of the student's work.
A discussion of the rubric when a task is set is also useful. It means that students can use it as a checklist as they draft and before they submit their work. For those students who do this well, perhaps in a group, it gives them a deeper understanding of the structure of their essays and renders subsequent feedback more effective. This also means that time spent in feedback sessions can be reduced.