My sister worked with the Navajo years ago. Some of their youngsters were being evaluated as low IQ, until they had been in an educational environment for awhile. They simply hadn't enough exposure to the world for the IQ test to evaluate their potential.
When my grandson was in the second grade we were told the IQ tests he was being given were inappropriate for him because he was obviously a very high IQ child. He is 10 now and in the 11th grade. He has been known to score very low on a test just because he is fed up with the continual testing the put him thru and marks things wrong on purpose.
@ConstitutionRose @Quix @CatherineofAragon @mystery-ak @Freya I did the same thing when in elementary school, but for a different reason. It was a scholastic aptitude test given to the class. It was multiple choice and I knew the right answer to the question but one of the choices was a cowboy in the movies and he was my favorite cowboy, so I selected his name knowing it was wrong. An evaluator needs to know the mind set of the person being tested.
When I was an associate school psychologist, a principal of a school asked me to test a certain student as he was causing a problem with him, and a problem in class and his teacher also thought he had a sex problem. He was in the 5th grade. I began the testing and realized this child was brilliant. I asked him what he thought of the principal and he said, "He overreacts." (definition of overreacts: respond more emotionally or forcibly than is justified). This kid was right as that is what I thought of the principal.
His father was an engineer and this kid was studying his father's advanced math books at home. The kid told me when school starts he has to sit through what he learned the year before and the class was boring. The teacher would not let him bring an advanced math book to class to study while the others were on boring math questions. Also, when the teacher would make a mistake, this kid would point it out.
About his "sex" problem: Halloween had happened the night before and the kids brought their sacks of goodies to school they got that night before. Well, someone had put a woman's bra in his sack so it was in there. The teacher went nuts. That was the kid's "sex" problem.
I recommended to the principal that he move the kid out of the 5th grade into the 6th grade which was junior high school (he would be out of this elementary school). The principal was delighted to get rid of this "problem" kid.