One of the most effective techniques to reduce energy consumption in conditioned buildings and achieve thermal comfort (through reduction of indoor temperature) in naturally ventilated or hybrid buildings is the incorporation of passive design strategies or bioclimatic architecture. Thermal comfort—the most important parameter of Indoor Environment Quality (IEQ)—has profound implications on occupant health and well-being. The passive strategies generally recommended to improve thermal comfort for warm-humid climates are cross-ventilation and the use of low thermal mass materials. However, these passive strategies may not be appropriate for school classrooms as they are operated only during the daytime for class hours. This paper presents the empirical data captured in-class hours during the hottest month of the year, to understand the thermal condition of school classrooms, and its analysis to identify appropriate passive strategies for warm-humid climates. Results indicate that the indoor temperature was lower than the outdoor temperature during the class hours and vice versa during the night hours. This led to the conclusion that cross-ventilation with low thermal mass as passive strategies would worsen the thermal condition during class hours. Further, recommendations are made on the most appropriate passive strategies, such as compact planning (double-loaded corridor); stack ventilation during class hours; nocturnal ventilation during off-hours with high thermal mass; etc. While thermal comfort is only one parameter affecting students’ learning, this study reveals the need to empirically assess the appropriateness and effectiveness of all generalized recommendations by codes, standards, and tools for specific cases.