Lesson 3 of 12
Objective: SWBAT identify and describe the physical and chemical properties on which minerals are classified and how they are used | SWBAT use Moh’s Scale of Hardness to classify and identify minerals | SWBAT interpret the ‘Properties of Common Minerals’ table on the ESRT
[Note: For additional information, including embedded checks for understanding and teacher directions, refer to the attached Word document at the bottom of this page, which has embedded comments alongside the resource.]
This lesson serves as another introductory lesson to mineral properties, and continues to lead toward mastery in the NGSS Standard MS-ESS2-1, which asks students to: Develop a model to describe the cycling of Earth's materials and the flow of energy that drives this process. As explained in the NGSS standards document, the formation of rocks and minerals is encompassed in the development of a model that "describes the cycling of Earth's materials." Since rocks and minerals are integral components that cycle over time, this lesson directly addresses how scientists go about identifying minerals on and in Earth's surface.
In relation to content, this lesson is fairly vocabulary-intensive, and featured a lot of up-front learning of new words and phrases (some, like luster, they have learned in previous years). After the initial vocabulary section, they get into using Moh's Hardness scale to identify minerals using various mineral samples. Finally, there are some Regents questions for them to practice with before a summative exit ticket for the lesson.
Do Now & Objective(s)
Students enter silently. When the timer is complete, we will go over the answers together (a combination of 'cold calling' and volunteers, usually). Then, a volunteer is asked to read the objective.
After the 'Do Now,' I have students each receive a small sample of halite (a transparent salt crystal). I ask them to examine both their pieces and the larger piece in the front of the room (I have a large, cubic sample) for either cleavage or fracture (halite experiences cubic cleavage). I then ask them to talk for about 30 seconds to discuss any properties that they notice about the mineral. Then, I instruct them to taste it (it has a distinct salty taste), and then ask them to use the back page (16) of their ESRTs to determine what the mineral is. [Note: Under "distinguishing characteristics", it is noted that halite has a "salty taste"]
After this, students take down some notes on physical properties of minerals while I do the same on a document camera at the front of the room. [Note: The attached lesson as a Microsoft Word document has embedded comments with definitions filled in for the guided notes]. After providing the definitions, I ask them to locate the words on the back page (16) of their ESRT(s). [Note: For luster, it helps to provide samples for them to distinguish between metallic and non-metallic luster. I usually pass around a sample of graphite and a sample of calcite as two minerals that clearly exhibit metallic and non-metallic luster, respectively.]
Mohs' Hardness Scale
In the next section, students will demonstrate Mohs' Hardness scale with some mineral samples. As indicated in the attached lesson document, a mineral can only be scratched by something with a greater hardness. First, students will be able to test a piece of talc with their fingernail. Then, they'll work with a sample of fluorite, eventually using a nail to scratch it (the idea being that anything with a higher hardness number can scratch anything with a lower hardness number). This is done as a brief preparation for the next lesson's lab, where they will be determining hardness for an unidentified mineral set to help determine which mineral it is.
After the brief demonstrations with talc and fluorite, students write down their response (reference the attached resource) on the handout concerning a piece of feldspar.
After working with mineral hardness and physical properties, we transition back to the last page of the ESRT, and students also get the chance to try their hand at some mineral-focused Regents questions in this section of independent practice. Given that the table itself is relatively straightforward (with clearly delineated columns and rows), and they've had an opportunity to explore it and use it in the earlier section in class, I find that students are already using the chart fluidly by this time - I don't often find a need for more than cursory levels of explicit instruction here [Note: The only two things that need some careful looking at are the columns on luster (as they can be a bit confusing the first time they're looked at, and the element key at the bottom (mostly because students often don't realize it's there)].
Exit Ticket & Closing
In the last section, students are given several minutes to complete the Exit Ticket before it is collectively graded as a class (I usually have students grade their own or "trade and grade" with a seatmate or nearby partner). Then, one or two students are asked some summary questions ("What's the difference between metallic and non-metallic luster?" | "What determines a mineral's physical properties?") before all students are dismissed for the day.