The NCLB requires that students in grades 3 through 8 be tested annually in reading and math and twice in science. The Iowa Test is an example of a standard achievement test for primary education. It tests vocabulary, reading comprehension and listening, language and social studies, math, and science and is used to help school systems determine students' strengths and weaknesses, to track their educational growth and to establish a baseline for testing in subsequent years. Schools then use the information from standardized tests to set the curriculum and determine where changes are needed.
The NCLB requires students in 10th through 12th grade to be tested at least once in reading, math and science. The Iowa Test, in addition to the areas tested in primary school, tests language (spelling, capitalization and punctuation), math (concepts, estimation, problem solving, computation and data interpretation), maps and diagrams and students' understanding of reference materials. The results are also used to determine school curricula, students' strengths and weaknesses and to inform parents where students may need additional help.
Most universities require that students take a college entrance standardized test, of which the SAT and ACT are the standards. The ACT tests English, math, reading and science, assesses students' educational development and tests whether they will be able to complete college-level studies. The highest possible score is 36.
The SAT is broken into two parts, each worth a maximum of 800 points for a total of 1600. The first part tests critical reading, math and writing while the second covers 20 different subjects and tests students' overall knowledge. Many students also take the practice versions---the PLAN (ACT) and PSAT (SAT)---as high school sophomores. National Merit Scholars are awarded based on the PSAT results.
Most graduate school programs require a specific standardized test before considering an applicant. To enter law school you must take the LSAT and medical school requires the MCAT, but most other graduate programs require the GMAT or GRE. The score requirements vary by school but because the tests are the same for everyone, they strike a balance between schools that may have varying curricula.