This combination of undated images taken from video provided by Julia Anne Leonard shows a "handoff" of a baby handing the toy to the parent, left, or throwing the toy to the ground during a study conducted by researchers. Children around 15 months old can become more persistent in pursuing a goal if they’ve just seen an adult succeed after struggling, a new study says. The results suggest “the potential value in letting children ‘see you sweat:’ Showing children that hard work might encourage them to work hard too,” researchers conclude in a report released Thursday, Sept. 21, 2017, by the journal Science. (Julia Anne Leonard via AP)