Recent work on adult metacognition indicates that although metacognitive monitoring often guides control operations, sometimes it follows control operations and is based on the feedback from them. Consistent with this view, in self-paced learning, judgments of learning (JOLs) made at the end of each study trial "decreased" with the amount of time spent studying the item, suggesting that JOLs are based on the memorizing effort heuristic that easily learned items are more likely to be remembered. Study 1 extended investigation to primary school children. Whereas for third to sixth graders (9- to 12-year-olds) JOLs decreased with increasing study time (ST), no such relationship was found for first and second graders (7- and 8-year-olds). For both age groups, however, recall decreased with ST, supporting the validity of the memorizing effort heuristic. Self-reports (Study 2) disclosed the belief that recall should tend to increase with ST. The results bring to the fore the importance of mnemonic cues that shape metacognitive feelings even among primary school children. These cues lie in the very feedback that learners gain on-line from task performance rather than in metacognitive knowledge, and their use may also contribute to increased monitoring accuracy with age. (Contains 1 figure and 1 table.)