This chapter explores different orientations to research practices that are present in both knowledge and interaction analysis. It analyzes differences associated with 'natural descriptive' (ND) and 'hidden machineries' (HM) orientations. Things like phenomenological primitive (p-prims) can play a role in implementing the functions of coordination classes, but the concept of coordination class, itself, is functional. P-prims have their functional aspects; they contribute feelings of confidence and naturalness, feelings of something's being wrong. The two cases, Charles Darwin and the theory of evolution and Ramon y Cajal and the neuron doctrine, illustrate the diversity of natural descriptive approaches across disciplinary fields in the natural sciences, and their interplay with hidden machinery types of work. The concept of legitimate peripheral participation (LPP) provides a structural, explanatory framework for a theory of 'situated learning' that is made up of changing social relations to ongoing practice.