Scrapbookers lump together items they consider scrapworthy and split them from the rest which they consider to be not scrapworthy (i.e., trashworthy or forgettable). Scrapworthiness is shaped by how scrapbookers classify their lives within their scrapbooks.
For example, a scrapbooker may consider both holidays and their family as scrapworthy, but they only scrapbook holidays their family celebrates in some way. Even then, not all celebrated holidays are scrapbooked.
Moreover, scrapbookers also chronicle non-holiday family events in scrapbooks. In this way a child’s high school graduation (family) is mentally closer to Christmas (family and holiday) than Labor Day (holiday) is to Christmas (holiday and family). Family is lumped together with family and split off from holidays, though holidays could be lumped together and split off from family.
Scrapbooking then is a site to explore how lumping and splitting happens and where these mental quantum leaps occur (Zerubavel 1991).
Zerubavel, Eviatar. 1991. The Fine Line: Making Distinctions in Everyday Life. Chicago, IL: The University of Chicago Press. (Public Library)