Concept Inventory

A concept inventory is a criterion-referenced test designed to evaluate whether a student has an accurate working knowledge of a specific set of concepts. To ensure interpretability, it is common to have multiple items that address a single idea. Typically, concept inventories are organized as multiple-choice tests in order to ensure that they are scored in a reproducible manner, a feature that also facilitates administration in large classes. Unlike a typical, teacher-made multiple-choice test, questions and response choices on concept inventories are the subject of extensive research. The aims of the research include ascertaining (a) the range of what individuals think a particular question is asking and (b) the most common responses to the questions. Concept inventories are evaluated to ensure test reliability and validity. In its final form, each question includes one correct answer and several distractors. The distractors are incorrect answers that are usually (but not always) based on students' commonly held misconceptions.

Ideally, a score on a criterion-referenced test reflects the amount of content knowledge a student has mastered. Criterion-referenced tests differ from norm-referenced tests in that (in theory) the former is not used to compare an individual's score to the scores of the group. Ordinarily, the purpose of a criterion-referenced test is to ascertain whether a student mastered a predetermined amount of content knowledge; upon obtaining a test score that is at or above a cutoff score, the student can move on to study a body of content knowledge that follows next in a learning sequence. In general, item difficulty values ranging between 30% and 70% are best able to provide information about student understanding.

Distractors are often based on ideas commonly held by students, as determined by years of research on misconceptions. Test developers often research student misconceptions by examining students' responses to open-ended essay questions and conducting "think-aloud" interviews with students. The distractors chosen by students help researchers understand student thinking and give instructors insights into students' prior knowledge (and, sometimes, firmly held beliefs). This foundation in research underlies instrument construction and design, and plays a role in helping educators obtain clues about students' ideas, scientific misconceptions, and didaskalogenic, that is, teacher-induced confusions and conceptual lacunae that interfere with learning.