The Instructional Process Analysis Project (IPA) is a study jointly undertaken by the Nordic countries in 1967. The present study discusses a methodological problem area of very narrow scope within the IPA project. The general aim of the study is to examine the factor-analytical method of sequence analysis and to produce variables that measure the appearance of sequential tendencies. Also, the study will measure the process from the starting point of transition probabilities between the elements. The specific aims fall within three main areas: a) the reliability of measures of classroom behavior and their practical utility, b) the inverse factor analysis of sequences of interaction that may occur within the framework of lessons and that characterize only the lessons of a certain type, and c) the factor analysis of sequences of interaction that occur within the framework of lessons and whose basic form remains the same but whose relative frequency varies from lesson to lesson. The first part of this report summarizes the contents of earlier reports. (JA)