Students referred to the term of energy for explaining the card of a sample or an object. Interestingly, students' explanations from Grade 1 to 6 were based on the use of energy or ideas relating to transformations of energy in the samples or objects depicted by the cards. For example, cards of battery, factory, power plant, and dam were usually explained by stating that these use energy, and finally these forms of energy are transformed into electric energy. Most students stated that a dam is generating energy or that the dam is "changing" water energy into electric energy. Leo (Grade 1), for example, stated that dam is producing electric energy from water energy.