This paper presents the findings of a longitudinal study in which two instructional methods to teach agreement features to first-year university students specializing in Spanish in Japan are compared. On the one hand, the control group was exposed to the traditional top-down teaching of agreement paradigms and were instructed to practice them through pattern repetition. On the other, a bottom-up move informed by Vygotsky and Gal'perin's theories of conceptual formation was induced in the experimental group by using schemata and verbalization during the task of using agreement features. The data suggest that (a) the material expression of conceptual relationships (e.g. through schemata) and (b) the verbal rendition of rules or conceptual connections, and (c) the overall framing of the task as a bottom-up move actually helped acquirers in their mastery of gender and number agreement. The results of the intervention also support Kim and Kellogg (2006) and Centeno-Cortes and Jimenez Jimenez's (2004) paradoxical view that L1 conceptual elaboration and organization aimed at solving L2 language tasks plays an important role in L2 acquisition. The data seem to indicate that there is room for encouraging learners' hypothesis-making in the L1 under certain conditions, such as the kind of guided induction designed for this research and the one advanced by Herron and Tomasello (1992), and Tomasello and Herron's (1988a, 1988b). L2 native instructors who dismiss or suppress acquirers' talk in their L1 in their communication classes should assess if that talk is part of an important process of hypothesis-making or verbalization of language rules or not and act accordingly. L1 exchanges linked to hypothesis-making or task organization seem to foster L2 development and therefore should not be treated like a waste of time by "Communication" instructors. In sum, the bottom-up move within Vygotsky's ZPD is suggested as a feasible, although more elaborate intervention, as the findings on the intervention suggest. (Contains 5 figures and 3 tables.)