Based on a study of 50 children between the ages of 3;0 and 5;6, the reasons for the differential difficulty of various forms of "who,""why,""when," and "how" questions are postulated. (EJS)

In this study comprehension of sentences describing two events occurring simultaneously or in sequence was assessed in 5-, 7- and 9-year-old children. The sentences were at three different levels of linguistic complexity, differing only in whether simultaneity or sequentiality was described. Subjects were kindergarten, second, and fourth grade…