Item maps help to illustrate what students know and can do in NAEP subject areas by positioning descriptions of individual assessment items along the NAEP scale at each grade level. An item is placed at the point on the scale where students are more likely to give successful responses to it. The descriptions used in NAEP item maps focus on the knowledge and skills needed to respond successfully to the assessment item. For multiple-choice items, the description indicates the knowledge or skill demonstrated by selection of the correct option. For constructed-response items, the description takes into account the knowledge or skill specified by the different levels of scoring criteria for that item.
The map location for each question represents the probability that, at any given score point, 65 percent of the students (for a constructed-response question), 74 percent of the students (for a four-option multiple-choice question) or 72 percent of the students (for a five-option multiple-choice question) answered that question successfully. For constructed-response questions, responses could be completely or partially correct and therefore a question can map to several points on the scale.
For example, in the case of a four-option multiple-choice question in the 2005 NAEP mathematics assessment that maps at 276 on the scale, fourth-grade students with a score of 276 have a 74 percent chance of answering this question correctly. In other words, out of a sample of 100 students who scored 276, 74 would be expected to have answered this question correctly.
After each constructed-response item descriptor, there is a notation (e.g., "Superior," "Acceptable") that applies to the scoring guide used to score each item. (For constructed-response questions, responses could be completely or partially correct and therefore a question can map to several points on the scale.) Click on the item descriptor, and select "scoring guide" in the NAEP Questions Tool to read a description of each of the score levels.
(Note that NAEP does not report individual scores of students taking the NAEP assessments. The item map is a tool that helps researchers and educators evaluate the progress of the nation's students as a whole.)
Before each item descriptor is a symbol that identifies the content classification of the item. Descriptions of each classification are available in the framework for the subject.
Performance information about student groups by jurisdiction is available by clicking “compare student groups.” Once the jurisdiction and student group are chosen, the user has the option to see the results as a table or a graphic. If a graphic display is chosen, a box and whisker plot will appear next to the item map. The plot shows the range of performance for selected student groups. For example, the number corresponding with the point in the very center of the plot is the score at the 50th percentile, indicating that 50 percent of the students in the group scored at or below that score. The descriptions in the item map from the bottom to the point on the scale corresponding with the score of the 50th percentile reflect the knowledge and skills likely to be demonstrated by at least 50 percent of the particular group of students.