Children are on a quest for knowledge. To achieve it, children must integrate separate but related episodes of learning. The theoretical model of memory integration posits that the process is supported by component cognitive abilities. In turn, memory integration predicts accumulation of a knowledge base. We tested this model in two studies (data collected in 2016-2018) with second (8-year-olds; n = 391; 196 female; 36% Black, 27% Hispanic/Latinx, 29% White, and 8% multiracial) and third (9-year-olds; n = 282; 148 female; 36% Black, 31% Hispanic/Latinx, 27% White, and 5% multiracial) graders. The results support the theoretical model and the role of verbal comprehension in learning new information, and also indicate that verbal comprehension alone is not sufficient to build knowledge.