Various resources can be used to prevent from forgetting things: for example, habitual actions to use external memory devices, metamemory knowledge of external memory devices, script knowledge for planning, and others' aids. The availability of the resources is not equal for anyone, however. The purpose of the present study was to examine developmental changes in contents of the available resources and the relationships among the resources for elementary school children in their homes. The questionnaires concerning the resources were administered to seventy second graders, sixty-six fourth graders, seventy-one sixth graders, and their parents. As results, the children's knowledge increased with grades, while parental aids decreased with grades. Significant (marginally significant) correlation between children's knowledge and parental aids were found in fourth graders only. Moreover, there was a significant (marginally significant) correlation between children's habitual actions to put the room in order and children's script knowledge in fourth and sixth graders, although differences in habitual actions among graders were not significant.