UNIT 3: MODELING MATTER
CHAPTER 1
In Chapter 1, students are introduced to the context of the unit—they are food scientists working for Good Food Production, Inc. In this chapter, students use paper chromatography to separate a mixture of food dyes in order to determine whether it includes a potentially hazardous food dye. However, the real question they are trying to figure out is why the mixture of food coloring separated into different dyes. Students are introduced to the particulate model of matter and challenged to apply this newfound knowledge to answer the Chapter 1 Question Why does the food coloring separate into different dyes? Students go on to interpret, create, evaluate, and revise various models of chromatography, including a variety of physical models, computer models, and diagrams. Students learn that molecules can have different shapes, sizes, weight, and attraction to other molecules and that these properties are important in understanding how the process of chromatography works to separate mixtures of molecules.
CHAPTER 2
In Chapter 2, students are introduced to a new problem—creating a new salad dressing with a flavor, texture, and appearance that appeals to consumers. They begin by figuring out how to make a salad dressing without sediments. As they do, they are challenged to use their understanding of the particulate nature of matter and of the properties of molecules to explain why some solids dissolve, and others do not.
CHAPTER 3
In Chapter 3, students continue to work toward making a salad dressing with particular properties, shifting their focus to creating a salad dressing that will not separate into layers. They work to answer the questions What happens when you mix a liquid in a liquid? and What happens to the molecules of two liquids when you mix them together? Students first investigate at the observable level, with liquids that mix and don’t mix, and then investigate at the nanoscale in the Modeling Matter Simulation. Students construct nanovision models of liquids that mix and don’t mix and discuss why. In addition, students read Science You Can’t See in order to build on their understanding of how scientists make inferences about phenomena they cannot observe directly.