Scientific theories contain many propositions composed on the basis of the logic, i.e. the relationships among the theories. Such propositions cannot be confirmed by facts from experimentation and/or observation.
The existence of ions cannot be seen, but it is a very important concept for learners studying chemistry. However, it is very difficult for the junior high students to commit to the concept of the existence of ions, because there is a theoretical gap between some observed facts and their existence.
The purpose of this study is to have students commit to the idea of the existence of ions. In this study, the theory of Quine’s Holism was applied as the strategy of the classroom lesson. The students could commit to the idea of the existence of ions when the theoretical network of electrolysis, Volta’s battery, and the neutralization of acid and alkali were connected to each other by sharing the concept of ions on the concept map. The learners could successfully understand the ion as a pragmatic tool to explain their observations.