Binet and Simon assumed that children generally follow the same path of, so their primary goal in creating an assessment was to compare the mental abilities of an individual child with the mental abilities of other children in the same age category.

the missing word is intellectual development

Explanation:

Binet and Simon assumed that children generally follow the same path of intellectual development, so their primary goal in creating an assessment was to compare the mental abilities of an individual child with the mental abilities of other children in the same age category.

intellectual development means the growth of a child's ability to think and reason. It's also about how they organize their minds, ideas and thoughts to make sense of the world they live in for example how they begin to reason and argue, uses words like why and because.

4 because 4 is godly

i believe your answer is mountains.