The distinction between melting and dissolving is important in science, but may not be clear to younger learners. An ice cube placed in a glass of water will melt. A sugar cube placed in a glass of water will disappear in a similar way. In both cases the solid seems to slowly disappear.
Learners may describe both cases as being melting – something not helped by the way the word melt is commonly used metaphorically as when someone is said to 'melt into the night' (e.g., lithium chloride melts before your eyes).
Interestingly, even when learners know the dissolved substance (e.g. sugar) is still in some sense present (e.g., they know it makes 'the' water' taste sweet) they may assume the weight of the solid has also disappeared once it is no longer visible and so the container with the solution will weight less than when the solid was added.
Read about the nature of alternative conceptions
Read about some examples of science misconceptions
Read about historical scientific conceptions
