of an event to the latest stop of the event. Finally, frequency is the total number of times the selected event (e.g., teacher labelingvocabulary) occurs in the observation. For this study, we were particularly interested in how the instruction and interaction opportunities were distributed according to the cognitive complexity of vocabulary tasks. Specifically, we were interested in determining whether tasks that requested students to label or define a vocabulary word (i.e., tasks at the lower end of cognitive complexity) would differentially influence vocabulary development less than tasks focused on higher-order tasks,such as associating new vocabulary with previously taught words and/or contrasting examples.