What Are the Critical Features of CBM?
CBM is a reliable and valid assessment system for monitoring student progress in basic academic skill areas, such as reading, writing, spelling, and mathematics (Deno, 1985, 1992, 2003; Shinn, 1989). CBM is an alternative assessment system that also borrows some features from standardized, norm-referenced assessment. The CBM procedures, including test administration, scoring, and interpretation, are standardized; that is, tests are given and scored in the same way each time. The content of the CBM tests may be drawn from a specific curriculum or may represent generalized outcomes for a student at that grade level. In either case, CBM test content represents important, global outcomes for the year and not just an individual objective or series of objectives representing current instructional lessons. Teachers give short, alternate assessments of these important, grade-level skills once or twice each week across the year and plot student scores on a graph. Thus, teachers are able to use CBM in a formative way to gauge student progress over time.
CBM Procedures in Reading
For reading measurement, oral reading fluency on grade-level passages in which the student is expected to be proficient by year’s end constitutes the CBM score. Oral reading fluency is a quick, reliable measure that correlates highly with reading comprehension (Deno, 1985). Students who are fluent readers typically are good comprehenders; they are able to devote attention to the meaning of the text. Similarly, slow readers tend to comprehend little. Thus, the CBM score represents overall reading achievement. The teacher randomly selects a passage from the pool of selections that represent reading mastery by the end of the year. The teacher tells the student where to begin reading aloud and times the student for 1 minute. Omissions, mispronunciations, and transpositions are recorded as errors. Insertions are ignored, and self-corrections are counted as correct if supplied within 3 seconds. If a student pauses longer than 3 seconds when trying to say a word, the teacher can supply the word but also marks that word as an error. The total number of words read correctly in 1 minute comprises the CBM score plotted on the graph.
CBM Procedures in Mathematics
For either mathematics computation (e.g., addition, subtraction, multiplication, and division with whole numbers, fractions, and decimals) or mathematics concepts and applications (e.g., place value, time and money, charts and graphs, and problem solving), the teacher identifies 25 problems that represent the important skills to be mastered by the end of the year. Alternate forms of 25 problems then are developed with each form containing the same proportion of problem types at the same level of difficulty but using different numerals. Commercially prepared alternate forms are available for elementary and some middle school grades (e.g., L. S. Fuchs, Hamlett, & Fuchs, 1998, 1999). Depending on grade level and type of mathematics test (i.e., computation vs. concepts and applications), the teacher allots 2-8 minutes for students to work, although the time allowance never changes across the year for a particular student/grade level. Thus, mathematics fluency as well as accuracy is addressed by this measure, and scores can be compared. The CBM score is derived by determining the number of correct digits in the student’s final answers per specified unit of time.