The fact that children tend to perform more similarly on two different tests of spatial visualization than they do on a test of spatial visualization and a test of perceptual speed supports the usefulness of:

dividing intelligence into seven primary mental abilities.
scholastic achievement tests.
thinking of intelligence as a single trait.
science and math classes.

dividing intelligence into seven primary mental abilities.  

Explanation:

Research reports suggest that intelligence in individuals are linked to seven factors which are referred to as primary abilities, these are; word fluency, verbal comprehension, spatial visualization, number facility, associative memory, reasoning, and perceptual speed. This is the reason why a child will perform well on a particular area than the other, that is, the child may perform better and similarly in a series of spatial visualization test if that is his/her primary ability than if he is given a test on perception which is not his/her area of ability.

i honestly have no idea

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