AbstractThis study is aimed at investigating the relationships among students' relevant prior knowledge, meaningful learning orientation, reasoning ability, self-efficacy, locus of control, attitudes toward biology and achievement with the human circulatory system (HCS) usi ng the learning cycle (LC) and the traditional classroom setting. The study was conducted with two teachers and four classes for a total of 60 11th grade students from high school. One class for each teacher was assigned as an experimental group and treated with 5E LC instruction and the other class was assigned as a control group and treated with traditional instruction (TI). The Human Circulatory System Achievement Test (HCSACT) was administered twice as a pre-test and after the treatment period, as a post-test to both the experimental and control groups. The Learning Approach Questionnaire, Test of Logical Thi nking, Self- Efficacy Scale, Locus of Control Scale and Attitude toward Biology Scale were also administered to all students. The results indicated that the LC improved students' achievement in the HCSACT compared to TI. Stepwise multiple regression analysis revealed that in the learning cycle classrooms, the main predictors of achievement on the HCSACT were students' reasoning ability (45.8%) and their prior knowledge (15.9%). In traditional classrooms, students' meaningful learning orientation (40%) and locus of control (9.8%) were the main predictors of achievement.KeywordsCognitive Variables, Human Circulatory System, Motivation, Learning Cycle.Ozlem SADIaResearch offers alternative strategies to improve meaningful learning in science. To promote meaningful learning, students can be encouraged to transfer theoretical knowledge into practical applications and to make connections between their pre-knowledge and new knowledge (Ausubel, 1963; Novak, 2002). The inquiry-based learning model has had a great influence on students' meaningful learning, and the model is one of the active learning models which includes not only asking question but also investigating, analyzing, and discussing subjects.The inquiry process encourages students to be active learners. Otherwise, rote learning occurs and several units and concepts can become unfamiliar and difficult to remember for students. Researchers state that rote learning leads to less understanding of scientific concepts and also generates misconceptions concerning those concepts (Williams & Cavallo, 1995). Especially in biology, the topics or concepts in each unit are closely related with each other, the human circulatory system being among such topics. According to the research, major concepts of the circulatory system which students do not fully understand are the structure and function of the human cardiovascular system, pumping mechanism of the heart, circulatory/respiratory relationships, systemic/ pulmonary circulation, closed circulation, type of blood vessels, homeostasis, and the blood flow rate (Alkhawaldeh, 2007; Arnaudin & Mintzes, 1985; Kwen, 2005; Sungur, Tekkaya & Geban, 2001; Windschitl, 2001; Yip, 1998). Students should connect each circulatory system concept with each other in a meaningful way in order to recognize better other biological concepts such as the digestive system, immune system and respiratory system (Alkhawaldeh, 2007).Research on the Learning CycleOver the years, most of the educational research studies have presented different learning approaches to support meaningful learning in science. One of them is the learning cycle, an inquiry-based teaching strategy derived from Piaget's model of mental functioning. The learning cycle can be defined as an instructional model based on constructivist epistemology that promotes conceptual change.There have been many studies carried out to assess the effectiveness of the learning cycle (Atay & Tekkaya, 2008; Balci, Cakiroglu & Tekkaya, 2006; Lee, 2003; Ates, 2005; Temel, Yilmaz, & Ozgur, 2013; Yadav & Mishra, 2013). …