It can also be useful to see how the percentile or grade equivalent scores change with one or two raw score points. The fewer questions per concept there are on an achievement test may cause significant variation in the precentile or grade equivalent scores as a result of single point variation in the student's raw test score. Achievement test scores may also include standard scores. These scores look a lot like IQ scores, but should not be confused with actual IQ scores, which measure different constructs. Jon may have received a standard score of 145 in math, and 128 in reading.
Achievement tests cover a fixed body of knowledge.
If Jon's school did not teach the specific facts included on the test, Jon might score poorly even though he is very bright. On the other hand, Jon's standard score of 145 in math indicates a highly achieving child, perhaps due to the fact he was exposed to the material, and demonstrated an exceptionally high level of mastery. Intelligence tests are often used to determine a student's placement in a school's gifted program. Intelligence tests may be given in a group or individual situation, however the individual types are generally more accurate. Group tests are often given as a screening tool, with more information gained through individual testing by a psychologist of those students who qualify based on the group test.