This study aimed to investigate and compare knowledge, attitudes and participating behaviors of students who participated in a training session. A training manual based on the participatory process was used. The sample consisted of 30 grade 5 students and 30 grade 6 students using a voluntary sampling technique. Research instruments included 1) a training manual for participation in environmental conservation, 2) a test on knowledge about environment, 3) scale on attitudes towards participation in environmental conservation, and 4) a questionnaire about participatory behaviors in environmental conservation. The major findings revealed that the developed training manual had an effectiveness index of 0.586. The students as a whole and as classified according to sex and grade level showed gains in knowledge, attitudes and behaviors before participating in the training session. The female students indicated more knowledge as a whole and in 3 aspects: garbage and sewage disposal, water conservation, and chemical usage than the male students. The grade 6 students evidenced more knowledge in the aspect of energy conservation than the grade 5 students. But these two groups of the students did not indicate attitudes and behaviors differently. Also, the statistical interactions of sex with grade level on knowledge and behaviors were found to be significant.