2021 Volume 62 Issue 2 Pages 457-464
This study is about the conservation of matter in aqueous solutions for 5th grade elementary school children. The children’s views of matter were clarified. Among the children, there are two ideas that salt is gone because it is no longer visible and the idea that salt is there even though it is not visible, in salt water. In the idea that there is no salt in salt water, the child believes that taste and weight are not attributes of salt, but are independent of it. The idea that salt does not disappear in salt water includes two theories: the particle theory and the melting theory. The two theories, “salt exists” and “salt does not exist” in the salt water can both explain following observed facts: salt dissolves and becomes invisible; salt water has a taste and preserves the weight of salt; and salt appears when salt water evaporates. In the end, the observed facts cannot determine either of these two theories. Therefore, instead of demonstrating each observation and experiment independently, we treated them as a whole and used simplicity and consistency as criteria for judging theories. Through this method, the children were able to understand the scientific theory that there is salt in salt water even though they cannot see it.
