What Is the Iowa Test? The ITBS and Iowa Assessments Explained

The Iowa test refers to the Iowa Assessments, the successor to the Iowa Tests of Basic Skills (ITBS), a norm-referenced achievement battery for kindergarten through high school now published by Riverside Insights. Launched at the University of Iowa in 1935, it is one of the oldest standardized achievement tests in the world. Current forms cover reading, language, math, science, and social studies, on paper or online, and report national percentile ranks along with growth-oriented standard scores. It measures what students have learned, which makes it an achievement test, and its publisher pairs it with a separate cognitive ability test when schools want to measure reasoning.

The Iowa program grew out of work by E. F. Lindquist (1901-1978), a University of Iowa professor who became one of the founders of modern educational measurement. A statewide academic contest that began in 1929, remembered as the "Brain Derby," led to the Iowa Every-Pupil Achievement Tests in the 1930s, and in 1935 to the Iowa Tests of Basic Skills for grades 6 through 8, extended to younger grades in 1940. The Iowa Tests of Educational Development followed in 1942 for high schoolers. Lindquist's influence went beyond the tests themselves: his center unveiled a high-speed electronic scoring machine in 1953, and his program supplied the foundations for the ACT, launched in 1959.

Riverside Insights publishes the current Iowa Assessments in Forms E, F, and G, spanning levels for kindergarten through high school. The Complete Battery covers reading, language, math, science, and social studies; a shorter Survey Battery covers reading, language, and math. All items are multiple-choice, and schools can administer the test on paper, including large-print and braille editions, or online. In 2025 Riverside released new norms built from a nationally representative sample of 4.6 million student records, updating the yardstick for post-pandemic achievement.

• Standard Score: A single equal-interval growth scale that runs continuously from about 80 in kindergarten to 400 at grade 12, used for tracking progress across years.

• National Percentile Rank: The percentage of same-grade students nationwide who scored lower; the 50th percentile is average.

• Stanines and grade equivalents: Stanines compress performance into nine bands with 5 as average; grade equivalents express performance against typical students at each grade level.

Note that an Iowa Standard Score of 130 means something completely different from an IQ of 130: the Iowa number sits on a vertical achievement scale that rises as children learn, while IQ is an age-normed deviation score centered on 100.

No. The Iowa Assessments measure acquired academic skills. Riverside publishes a separate instrument, the CogAT, to measure reasoning ability, and the Iowa is often administered alongside it so educators can compare a student's skills with their readiness to learn. Ohio's approved gifted-assessment list files every Iowa battery under achievement tests, used to identify specific academic ability at or above the 95th national percentile, while intelligence tests serve the superior-cognitive category. Research finds substantial correlations between cognitive-ability scores and ITBS achievement, which is expected: learning ability drives learning. But the constructs, and the tests, remain distinct, as our overview of aptitude versus achievement testing also shows in the adult-education world.

Levels run from kindergarten through high school, with the Complete Battery most common in elementary and middle grades.

Percentile rank is the clearest measure: 50 is the national average, and many gifted programs look for the 95th percentile or higher on relevant subtests.

Yes, in lineage: the Iowa Tests of Basic Skills was renamed and redeveloped as the Iowa Assessments in current Forms E, F, and G.

It measures learned academic skills. Reasoning ability is measured by companion instruments such as the CogAT, or by true IQ tests, as covered in what IQ tests are and how they work.

1. Canivez, G. L. (2000). Predictive and construct validity of the Developing Cognitive Abilities Test: Relations with the Iowa Tests of Basic Skills. Psychology in the Schools, 37(2), 107-113. doi.org/10.1002/(SICI)1520-6807

2. University of Iowa Press. (2009). Everett Franklin Lindquist. In The biographical dictionary of Iowa. uipress.lib.uiowa.edu

3. Frey, B. B. (Ed.). (2018). Iowa Tests of Basic Skills. In The SAGE encyclopedia of educational research, measurement, and evaluation. SAGE. doi.org/10.4135/9781506326139.n349

4. Riverside Insights. (2025, August 25). New Iowa Assessments norms for 2025. riversideinsights.com