The "bones" are, roughly, a core curriculum.
Though each tool might be used individually, or the toolbox might be used without the treasure-chest, it is assumed that most designers will want to move beyond the core curriculum.
The bones of Toolboxes and Treasure-chests are; perceptual (environmental) psychology, physical and intellectual depth (including play), functionalism, and identification.
The Computer Programmer's Guide to Child-rearing
Auxiliary Elements for document intro.abouttbtc.fishbones.htm
Part of Toolboxes and Treasure-chests.