Meaning 1 - A material uses as a medium for learning transfers from a teacher to a learner. (Chaiyong, 1989: 72)
Meaning 2 - A concern about a student learning that helps for more understanding, skill, and efficiency development according to the learning objectives. (Suwat, 1994: 53)
Meaning 3 - Learning tool with a development that a learner can learn by him / her own as an important point. (Department of Curriculum and Instruction Development, 2001: 213)
Meaning 4 - A material that contains a learning content or equipment that uses to teach a learner. (Kidanan
Malithong, 2002: 60)