Background of the study: Physical activity is any skeletal muscle-generated energy expenditure, according to the WHO. Regular exercise improves mental and physical health. To promote health, people of all ages and abilities should be more active and less sedentary. Purpose: The purpose of this research is to quantify the extent to which schoolchildren engage in physical activity during the school day. Methodology: The methodology employed in this study is that of quantitative research, and the research design chosen was a cross-sectional one. The investigation was conducted in a chosen Trichy school. Students in the sixth, seventh, eighth, and ninth grades made up the study population. The overall sample size for the study was sixty people, and its samples were picked using convenience sampling methods. A preplanned questionnaire was used to compile the information. The Physical Activity Questionnaire for Older Children (PAQ-C), by Kent C. Kowalski, is a standardized tool. Interviews were conducted to gather information, and both descriptive and inferential statistics were used to make sense of the results. Results: Most samples (49, or 98.0%) were moderately active. Low physical activity was found in sample 1 (2.0%). The mean weight was 146.99, the SD was 7.75. The average sample height was 40.84, with a standard deviation of 12.12. BMI averaged 18.67, with a standard deviation of 4.25. BMI variation was 18.11 and mean percentage was 29.53. Diet and mother's education were found to be linked with physical activity levels (p < 0.05). Conclusion: This study underlines the importance of physical activity in preventing non-communicable diseases including obesity and hypertension in schoolchildren. Primary prevention methods, such as mandated physical education programs, can reduce non-communicable diseases and their long-term effects on students.