Metamorphic Rocks I

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Objective

SWBAT identify and describe how metamorphic rocks are formed and explain the three (3) unique characteristics of metamorphic rocks, including: 1) banding 2) distorted structure 3) contact metamorphism

Big Idea

Students identify the key features of metamorphic rocks, in addition to exploring the concept of contact metamorphism

Introduction

[Note: For embedded comments, checks for understanding (CFUs), and key additional information on transitions and key parts of the lesson not necessarily included in the below narrative, please go to the comments in the following document: 1.10 - Metamorphic Rock Formation I (Whole Lesson w/comments). Additionally, if you would like all of the resources together in a PDF document, that can be accessed as a complete resource here: 1.10 - Metamorphic Rock Formation I (Whole Lesson)[PDF]. Finally, students may need their Earth Science Reference Tables [ESRT] for parts of the lesson (a document used widely in the New York State Earth Science Regents course) as well.]

This lesson is similar to the two previous lessons (located here and here, respectively) in that it primarily revolves around information found in the Earth Science Reference Tables [ESRT] [Note: Instead of using the entire Earth Science Reference Tables [ESRT], you may want to use just the page with the appropriate Metamorphic rock chart on it, which is located here as a PDF: Metamorphic Rock Chart [ESRT]]. This lesson focuses on the properties of metamorphic rocks that help in its identification, most notably characteristics such as banding and foliation. There is also an exploration of the properties of contact metamorphism, a process of "baking" the rock from nearby intrusions that result in low to mid-grade metamorphism. 

 

Do Now & Objective(s)

10 minutes

Students come in silently and complete the (attached) Do Now. After time expires (anywhere from 2-4 minutes depending on the type of Do Now and number of questions, although this one takes about 2 minutes), we collectively go over the responses (usually involving a series of cold calls and/or volunteers), before I call on a student and ask them to read the objective out loud to start the lesson.

As a general note, the Do Now serves a few purposes:

  1. It serves as a general review of the previous day's material;
  2. It is a re-activation of student knowledge to get them back into "student mode" and get them thinking about science after transitioning from another content area or alternate class;
  3. as a strategy for reviewing material students have struggled with (for example, using this as a focused review for material that they have struggled with on unit assessments or recent quizzes); and,
  4. It is an efficient and established routine for entering the classroom that is repeated each day with fidelity (I never let students enter the classroom talking. While it may seem potentially severe to have students enter silently each day, this is both a school wide expectation and a key component of my classroom. In many respects, I find that students readily enjoy the focus that starting with a quiet classrooms brings each day).

Properties of Metamorphic Rocks

20 minutes

After going over the Do Now and objective(s) for the day, the lesson begins by asking students to turn to the 'Scheme for Metamorphic Rock Identification' on the bottom of page 7 in their ESRT(s) (image also attached on the attached resource). They're usually given 1-2 minutes to collectively explore the chart, identifying any words, phrases, or rock names that might stand out to them. 

We then initiate a quick review by going over the processes that form metamorphic rocks (heat and pressure) and the definition of metamorphism. I give them a sample multiple choice question as a quick CFU before jumping right into some metamorphic rock identification.

I introduce banding and foliation by passing out some metamorphic rocks with those characteristics and asking students to identify any physical characteristics that they see in the rocks that are absent in both sedimentary and igneous rock types. Usually, they're able to identify the bands of minerals that are featured in the rock face, and the diagram on page 4 of the attached resource provides a representative image of how the molecules are rearranged via the process of metamorphism. 

We then, after a few minutes, transition into contact metamorphism. I usually have students go over the image on page 5 of the resource, read together in groups, and then use the image as a model. I explain that the symbols are types of igneous or sedimentary rocks, but when magma intrudes into sedimentary rock layers, it's capable of "baking" the rock, ultimately turning it into a type of metamorphic rock. Using the chart in their ESRT, they can identify the specific metamorphic rocks that are formed from particular sedimentary rock forms.

Practice

20 minutes

After this exploration and modeling, students are encouraged to practice the material with former Regents questions. In this section, students are urged to partner up for the first 5-6 questions, and then work independently for the latter half of the practice time. When there are about 6-8 minutes remaining, we usually go over the answers together before proceeding to the exit ticket for the day. 

Exit Ticket & Closing

10 minutes

In the last few minutes of class, I have students complete the daily Exit Ticket. For the sake of time, I have students grade them communally, with a key emphasis on particular questions and items that hit on the key ideas of the lesson (Note: This usually manifests as students self-grading, or having students do a "trade and grade" with their table partners). After students grade their exit tickets, they usually pass them in (so that I can analyze them) and track their exit ticket scores on a unit Exit Ticket Tracker. 

After students take a few seconds to track their scores, we usually wrap up in a similar way. I give students time to pack up their belongings, and I end the class at the objective, which is posted on the whiteboard, and ask students two questions:

  1. Do you feel that you mastered the objective for the day?
  2. Can you reiterate one thing you learned about ____________ (in this case, basic questions like the definition of radioactivity or half-life, etc.)