In order to investigate whether middle-class children use more complex sentences than

lower-class children, researchers divide 6 year old children into two groups: middle class

(family earns between $30 000 and $90 000 per year) and lower-class (family earns less than $30

000 per year). All children are then placed in a playroom with an adult, and the child’s

conversations are recorded. Researchers then count for each child the number of words per

sentence.