The results in Table indicate that the majority of students' responses from Grade 1 to 6 used the concept of electric energy to provide explanations about energy. Many Grade 1 - 3 students explained energy by referring to mechanical energy and forces and electric energy. Grade 4 - 6 students clarified their ideas about energy by referring to potential and electric energy. Upper primary school students referred to various forms of energy when they attempted to provide explanations about the cards presented to them. Additionally, it seemed that upper primary students were more inclined to refer to gravitational and chemical potential energy than lower primary students. Some upper primary school students mentioned that the dam, fuel, a dish of fish, and coal related to energy. Their explanations were mostly related to how a dam, fuel, a dish of fish, and coal "contained" energy after realizing that energy was transformed into other forms of energy. This indicated that upper primary students held the concept of energy transformations that helped them to mention more forms of energy. Although their explanations mentioned the concept of energy transformations, they did not mention how these cards related to a specific form of energy, but this was inferred indirectly. Thus, their explanations of energy transformations relating to the dam indicated that they considered the concept of gravitational potential energy, while their reference to fuel, coal, and a dish of fish clearly indicated that they implicitly exhibited the concept of chemical potential energy.
Grade 1 to 6 could not distinguish between forms and sources of energy. Although students usually considered the concept of energy transformations when they explained how the pictures in a card related to energy, they did not refer to several forms of energy, and they could not recognize energy degradation and the law of energy conservation. If they had a basic concept of the law of energy conservation, they might be able to suggest or consider energy degradation when referring to energy transformations. In fact, the law of energy conservation and energy degradation do not appear in Thailand primary school science curriculum