This study was a cross-sectional study, data collection
were from 1 January to 21 February. Target population
was students in Mahidol Withayanusorn high school
Grade 10 to 12 in Phuttamonthon District, Nakhon Pathom
province. Regarding calculated sample size, 270 students
were selected using Simple Random Sampling method
according to the number of classes.