This paper attempts to investigate the understanding of the law of mechanical energy conservation using a guided inquiry approach. A simple hands-on model was constructed and used to demonstrate the law of mechanical energy conservation. A total of 30 grade ten students from one of the middle secondary schools in western Bhutan participated in this pilot study. A single group pretest-posttest design was used. The participants were selected by purposive sampling method. The means of the pretest and posttest were determined to find the understanding of the law of mechanical energy conservation. The attitude survey questionnaire was used to explore the students' attitude towards the guided inquiry laboratory teaching using the hands-on model. A paired sample t-test showed that there was a statistical significant difference in the means of pretest (M = 13.43, SD = 3.766) and posttest (M = 21.67, SD = 2.893) at t(29) = -10.739, p = 0.000, a = 0.05 indicating an improvement due to the treatment. The attitudes of the students towards the developed learning unit were also found positive.