How old do you need to be to take an IQ test?

Answer 1

I.Q. stands for intelligence quotient. There are all sorts of instruments used to measure an individual's I.Q. One used in very young children is the "Draw-A-Man" test. Supposedly, if you ask a young child to draw a person, the child with a higher I.Q. will give the person more detailed features. (e.g. Eyebrows, Ears, Knees, etc)

A:

IQ tests can be administered to children as young as two years old. They are at their most accurate when given to preschool and grade school children; starting with high school, their accuracy drops off substantially.

This is because what's being measured is how much better at problem-solving the child is than other children their age, as compared to a baseline adult (usually considered to be around 18 years old). So the closer one gets to that baseline, the less predictive --and therefore, less accurate -- the test becomes.