A rubric is an explicit set of criteria used for assessing a particular type of work or performance. A rubric usually also includes levels of potential achievement for each criterion, and sometimes also includes work or performance samples that typify each of those levels. Levels of achievement are often given numerical scores. A summary score for the work being assessed may be produced by adding the scores for each criterion. The rubric may also include space for the judge to describe the reasons for each judgment or to make suggestions for the author (The TLT Group).