All IQ tests are structured so that about 50 percent of any population will score between 90 and 110. This would be a normal score and indicate that the person tested is capable of tasks designed for his age level. A 6-year-old with a l00 IQ can be expected to learn to read in first grade.
Deviations of 15 points above and below 100 encompass about 70 percent of a population. A bright 6-year-old with an IQ of 115 may learn to read somewhat faster than a child of the same age whose IQ is nearer to 100. This achievement would also depend on motivation, eyesight and dozens of other factors.
Two standard deviations of 15 are a range of 70 to 130. The 70 score indicates a mild level of disability, but given excellent instruction, this person will achieve somewhat below his age level. A score of 130 places the person in the gifted category where university graduate students and professors may be clustered.
Dependence on IQ tests can be a deterrent to a child's progress. A low score achieved on a day the child was ill may follow him throughout elementary school, causing him to be categorized as an average or below average student. It may be better to estimate a child's abilities based on his performance rather than to rely on test scores.