This study examines how specific classroom practices influence upper secondary students’ in-situ motivational experiences, including achievement emotions, value beliefs, and perceived support for mastery goals, autonomy, and competence (SMAC). Despite extensive research on motivation, research on the classroom application of this knowledge is still underdeveloped. Clarifying how motivation-supportive practices manifest in real classrooms, and how they relate to students’ lived experiences, is therefore essential for translating theory into pedagogical action. Within a one-year research–practice partnership, the authors and three teachers collaboratively designed and tested instructional elements aimed at promoting motivation. Twelve lessons were observed and qualitatively coded, and their characteristics were linked to students’ in situ experiences collected through experience sampling methodology. Relationships between instructional practices and student experiences were modelled using orthogonal partial least squares regression. The results show that practices emphasizing learning objectives were positively associated with students’ positive emotions, value beliefs, and SMAC, whereas doing objectives—framing goals in terms of task completion—were generally negatively associated. Clear lesson structure (e.g., expectations, planning) consistently predicted positive outcomes, while structural ambiguity showed negative associations. Relational support, such as showing genuine interest in students’ lives and their learning, further enhanced motivation. Feedback aligned with mastery-oriented goals was perceived less favourably in doingoriented contexts, suggesting that goal framing shapes how feedback is received. Overall, the findings illustrate how theoretically grounded principles of motivation can be enacted through subtle but deliberate instructional practices, offering actionable insights for implementing motivational theory in everyday teaching.