Children are active, curious learners. How might children’s curiosity shape their curriculum during word learning? Past research suggests that children’s tendency to explore can lead them to discover novel information during learning. This exploratory tendency could be especially useful when learning word meanings: exploring potential meanings for words broadly could help children efficiently probe a word’s possible extension. To investigate this question, we tested how children (5-8 years of age) and adults sample information when presented with a novel word and tasked with uncovering the word’s extension. Overall, we found that children explored novel word extensions conservatively. Children (as well as adults) favored sampling choices that confirmed a novel word meaning, as opposed to exploring broader possible meanings. Younger children’s sampling choices were especially conservative, with children often sampling the narrowest possible generalization option. Older children were more exploratory, probing broader possible word extensions more frequently. Counter to proposals that children are generally more exploratory at younger ages, our results suggest that when children test the extension of novel word meanings, they are often more likely to confirm their hypotheses than to explore.