This article is the first part of a twofold summary of the grounded theorizing in the RRREaT articles on the actual world, required assumptions, and preliminary empirical findings and results with the aim to contribute to clarifying what integrated measurement of cognitive-educational psychological phenomena can entail for studies that focus on persons and situations. This theoretical article is in alignment with a second article in which an integrated data-collection instrument for person-and-situation interaction is presented for empirical studies. The grounded theorizing for integrated measurement in both articles is illustrated via the phenomenon of active academic learning by connecting knowledge construction and person-and-situation interaction with the aim to understand learning behavioral decision-making. The layout in this article is threefold. First, the major components of active academic learning are reviewed to understand the theoretical concepts involved in students’ long-lasting cognitive knowledge construction, use and metacognitive knowledge of effective learning, and homework situation where learners can direct their learning for the larger part. Although many definitions of active academic learning exist, from a cognitive-educational psychological point of view, the major components are concentrating, information organizing via self-explaining, and memorizing, and a distinction is made between meta- and cognitive knowledge construction. Second, the learner’s homework situation, with its school tasks of learning, practice-exercises, and problem solving, is reviewed by summarizing the previous RRREaT articles on person-and-situation interaction. Third, the methodological consequences for integrated measurement to assess active academic learning in any self-acting required learning situation are presented via a theoretical framework for an integrated data-collection instrument, followed by assumptions, consequences, and theoretical solutions. This article especially goes into the issues of (a) collecting sufficient person-specific intra-individual data that still enables data analysis for establishing inter-individual groups, (b) obtaining an understanding of active learning behavior via the decision-making process of continuing feedback loops, and (c) obtaining an understanding of the objective and subjective situation across persons and time for the purpose of detecting inter-individual groups (e.g., via four-quadrant relationships). The final discussion is on integrated measurement for cognitive-educational psychological phenomena in general.