We spent a lot of time discussing what our evidence told us--that the substances we put into the water were still there but just so small! We then put these ideas into action and attempted to model them, especially as we're trying to figure out how the wastewater treatment facility may even get these dissolved solids out!
We developed some initial models for the dissolvability phenomenon, and here are some examples of student thinking. We agreed to "zoom-in" on both the substance entering the water and the water, too, as we agreed that the substance was still there but we just couldn't see it.
1.The zoom-in of the substance should show it made of pieces or particles. These zoom-in particles should be obviously bigger than in the cup.
2. The zoom-in of the substance in the water should show the pieces smaller than they are in the cup, because a substance that dissolves gets smaller when it enters water. The cup of water should NOT show visible pieces of the substance unless it's in the zoom-in.
3. The total weight of the pieces outside of the water and inside the water should be the same, as our weight test showed that no weight was lost.
4. Each substance that enters the water should be represented in a different way since they are all different substances--for example, citric acid is different than salt, so if citric acid is colored yellow, we can't use yellow to also represent salt.
We worked through our thinking to establish a consensu smodel, and here's what we came up with!