gains in the skills of identifying and controlling variables (11.29%) and interpreting data and drawing conclusion(11.83%). This may have arisen because the skill of identifying and controlling variables may have been difficult for students with low-science process skill (Beaumont-Walters & Soyibo, 2001). The skill of interpreting data and drawing conclusions was one of the complex integrated skills. To interpret data and draw conclusions correctly, students were required to have good basic skills and also the other four integrated skills. In this case, the supplemental skill development units or/and interventions should be considered (Bevins, et. al., 2001).