Exploring the Five Unknown Solids

In Lesson 2. students gained experience observing and describing properties of common objects. Now, students are challenged to observe and describe the properties of the five unknown, similar-looking white solids. Students will begin to observe how these chemicals are alike and different in texture, odor, and appearance. 

Our senses alone can tell us only so much. To extend our senses, we rely on technology—from simple magnifying lenses to enormously complex microscopes, for example. 

There are two kinds of properties physical and chemical. In this lesson, students explore the physical properties of each unknown that is, properties that can be observed without altering the chemical makeup of the material (e.g., color or shape). 

As you encourage students to make new discoveries, it may help you to keep in mind some examples of what past children have said  

Your students probably will come up with more ways to use their equipment and may suggest properties not mentioned here. 

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In this lesson, students use a third chemical liquid, red cabbage juice, to explore further the chemical properties unique to each unknown. Following the completion of this test, students analyze all the data they have collected over the past seven lessons and summarize what they now know about the physical and chemical properties of each of the five unknown solids. This is a good time for the class to add to the What We Think about Chemicals list from Lesson 1. 

In the last lesson, students explored some of the physical properties of the unknown solids. Over the next three lessons, they will continue this exploration by investigating the property of solubility. They do this by creating mixtures with each of the five unknowns and increasing amounts of water. This experience shows students that combining one substance with another can reveal new properties of each. 

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