1. Density CER Conclusion – Period 4
A substance will not always have the same density. Evidence 2 shows that when pressure increases, density also increases. When pressure increases, volume decreases but mass stays the same, so density has to increase. There is the same amount of mass in less space. In evidence 3, we see that temperature affects density. Warm ocean water rises while cool ocean water sinks. According to the table for evidence 4, the more salt there is in water, the more dense the water will be and the easier it will be for something to float in it. Evidence 5 is about the state of matter affecting density. The solid form of a substance will float or sink in its liquid form indicating that they have different densities. Therefore, we can conclude that a substance will not always have the same density.

2. Density CER Conclusion – Period 10/11
The density of a substance can change. Pressure affects the density of a gas. When pressure increases, mass stays the same but volume decreases. Therefore, the density of a gas can change due to pressure. Evidence 3 shows how temperature affects density. In the ocean, warm water rises and cold water sinks because they have different densities. Evidence 4 demonstrates that the Dead Sea contains so much salt that it is easier to float in than in regular water. The more salt is in the water, the more dense the water becomes. The presence of the dissolved salt changes the density of the water. Evidence 5 demonstrates that changing the state of matter of a substance can change the density. Frozen water floats in liquid water while frozen olive oil sinks in liquid olive oil. State of matter changes the density of these substances. A substance will not always have the same density. Pressure, temperature, state of matter, and presence of dissolved substances can change density.