We study how children develop a causal curriculum to achieve a challenging goal that is not solvable at first. Adopting the Procgen environments that include various challenging game tasks, we found that 5- to 7-year-old children actively used their current level competence to determine their next step in the curriculum and made improvements to their performance during this process as a result. This suggests that children treat their level competence as an intrinsic reward, and are motivated to master easier levels in order to do better at a more difficult one, even without explicit reward. However, our findings also suggest that children’s self-designed curricula may not always be the most effective design. Rather, repeatedly practicing on the difficult target task may be sufficient. Notably, when constrained to stay on the target task instead of crafting their own curricula, more children actually succeeded and made greater progress in the game, suggesting that children perceive a curriculum as beneficial, even when focusing on a singular difficulty might prove more effective.