Clusters are non-parallel test forms because content areas are spiraled throughout each cluster.
Each test form or cluster assesses a combination of reading, writing, language usage, science, social studies, mathematics content and mathematics process. Students are randomly assigned to testing groups. Random testing groups help to ensure that groups of students assigned to take each test cluster are heterogeneous in ability. In addition, random testing groups minimize influences on student performance that may occur when students are assessed in intact classroom groups by their regular classroom teachers. Test clusters are assigned randomly to testing groups within schools and across schools in each school system and the state.