How Does Chemical Weathering Change Earth's Surface?
Lesson 6 of 11
Objective: SWBAT explain how chemical weathering slowly changes the Earth's surface.
5e Lesson Plan Model
Many of my science lessons are based upon and taught using the 5E lesson plan model: Engage, Explore, Explain, Elaborate, and Evaluate. This lesson plan model allows me to incorporate a variety of learning opportunities and strategies for students. With multiple learning experiences, students can gain new ideas, demonstrate thinking, draw conclusions, develop critical thinking skills, and interact with peers through discussions and hands-on activities. With each stage in this lesson model, I select strategies that will serve students best for the concepts and content being delivered to them. These strategies were selected for this lesson to facilitate peer discussions, participation in a group activity, reflective learning practices, and accountability for learning.
The Earth's Changing Surface unit focuses on some processes that change Earth's surface slowly, over a long period of time, or abruptly. In order for students to develop an understanding that the surface is constantly changing, they take part in a variety of guided inquiries geared towards scaffolding this understanding. In the first part of the unit, students explore the structure of the Earth and processes that cause changes to it. These lessons include earthquakes, volcanoes, landslides, physical and chemical weathering, erosion and deposition. They need to develop an understanding of these processes and how they change the Earth's surface for the second part of the unit which focuses primarily on minerals, rocks, and the rock cycle. Students apply their understanding of these processes as they investigate the formation of rocks and the cycle of changes they go through in a lifetime.
In part 1- How Does Chemical Weathering Impact Earth's Surface lesson, students develop an understanding of how chemical weathering breaks down the materials on Earth's surface. They explore the weathering of rocks by conducting a simulation using chalk to represent a rock and vinegar to illustrate the effects of acid rain over time. After their simulation, students use the think-pair-share strategy with a set of predetermined questions I provide them to reflect upon the purpose of activity. This strategy allows them to do their own thinking, prepare a response to engage in a discussion with their peers, and get them ready apply scientific thinking to an extension activity in part 2 tomorrow.
Next Generation Science Standards
This lesson will address the following NGSS Standard(s):
ESS2 Earth's Systems
Earth’s major systems are the geosphere (solid and molten rock, soil, and sediments), the hydrosphere (water and ice), the atmosphere (air), and the biosphere (living things, including humans). These systems interact in multiple ways to affect Earth’s surface materials and processes. The ocean supports a variety of ecosystems and organisms, shapes land forms, and influences climate. Winds and clouds in the atmosphere interact with the land forms to determine patterns of weather.
I address this standard in fifth grade because the elementary school's within my district do not formally teach science; therefore my students enter middle school (fifth grade) with a limited science background. By engaging students with activities to support this NGSS standard, I am providing with them experiences that will provide them a foundation to for later lessons involving minerals, rocks, soil, and plants.
Why do I teach with this lesson?
I teach the part 1-How Does Chemical Weathering Change Earth's Surface lesson to help students develop a understanding that the Earth's surface, the crust, is shaped by different processes like chemical weathering. Students examine the effects of vinegar on chalk after applying it to the chalk for a period of time. The vinegar simulates acid rain upon rocks which is represented by the chalk. They respond to reflection questions that help process their experience and connection to the changes on Earth's surface as well as developing reasoning for these changes. Their observations and reflection are used in a guided discussion tomorrow on other physical forces that change the Earth's surface. I find it important to provide guided inquiries that build their vocabulary and understanding of concepts in order to facilitate scientific thinking for future inquiry lessons related to Earth's Changing Surface. These experiences provide them a foundation that will support their learning in later lessons involving processes that change the Earth slowly and rapidly.
Students are engaged in the following scientific and engineering Practices.
2.) Developing and Using Models: Students use chalk as a rock to test the cause and effect relationship of chemicals by adding vinegar to it. Students evaluate the outcome of the procedure to describe the effect of chemical weathering on rocks or land.
3.) Planning and Carrying Out Investigations: Students carry out an investigation to observe the effects of chemical weathering on rocks. Through this investigation they analyze the outcome, make observations to generate a claim and produce evidence to support this claim.
8.) Obtaining, evaluating, and communicating information: Students record observations and write claim statements about the effects of chemical weathering on land. They use their observations as evidence to draw conclusions while writing these statements
Part 1 of How Does Chemical Weathering Impact Earth's Surface lesson will correlate to other interdisciplinary areas. These Crosscutting Concepts include
2.) Cause and Effect: Students make observations of a chemically weathered chalk (vinegar on it) determine how acid rain causes rocks and land to be changed by a natural phenomena.
4.) Systems and Models: Student understand systems may react with different systems. In this case, air, water, and land interact and impact the Earth's surface. They create a model illustrating the effects of chemical weathering using air, vinegar, and chalk to represent air, water, and land interacting.
Disciplinary Core Ideas within this lesson include:
ESS2.A Earth Materials and Systems
Classroom Management Ideas
Importance of Modeling to Develop
Student Responsibility, Accountability, and Independence
Depending upon the time of year, this lesson is taught, teachers should consider modeling how groups should work together; establish group norms for activities, class discussions, and partner talks. In addition, it is important to model think aloud strategies. This will set up students to be more expressive and develop thinking skills during the activity. The first half of the year, I model what group work and/or talks “look like and sound like.” I intervene the moment students are off task with reminders and redirecting. By the second and last half of the year, I am able to ask students, “Who can give of three reminders for group activities to be successful?” Who can tell us two reminders for partner talks?” Students take responsibility for becoming successful learners. Again before teaching this lesson, consider the time of year, it may be necessary to do a lot of front loading to get students to eventually become more independent and transition through the lessons in a timely manner.
EXPLORE TEAMS (Pre-Set)
For time management purposes, I use “lab rats” where each student has a number on the back of his or her chair, 1,2,3,4 (students sit in groups of 4)and displayed on the board. For each explore activity, I switch up the roles randomly so students are experiencing different task responsibilities which include: Director, Materials Manager, Reporter, and Technician. It makes for smooth transitions and efficiency for set up, work, and clean-up.
I begin by saying to the students, "in our last lesson we explored physical weathering and discovered factors that contribute to rocks breaking down mechanically." I call on student volunteers to share out those factors.
After recalling physical weathering, I say, "today we are exploring another type of weathering." (I do not tell them what kind yet as I want them to discover it during a simulation) I continue stating they are examining and analyzing images carefully looking for similarities and differences between them. Then, using the Odd One Out strategy, they need to decide which image does not belong and why. I selected this strategy to use because it provides students the chance to analyze the relationship of the images on display in order to promote student discussion.
I tell students they are doing a classroom mingle to find a discussion partner. They walk around the room silently. When the beeper goes off, they pair up with the person closest to them, discuss their thoughts about the images displayed, and get ready to share with the class, the "odd one out and why." After the first round of class mingle I have the students do four more rounds with two more images and a new partner each time.
I randomly call upon a pair to share the image they believe is "Odd One out" and ask them to justify. I ask the rest of the class, "If you agree, give me a thumbs up. If you disagree, give me two hands in the air and be prepared to use our our disagree statements with, I respectfully disagree with _____ because..." With that said, I remind them they need to provide relevant evidence from our investigation in the previous lesson. After three rounds, I say, "Let's investigate why the features have changed the way they did."
Frontloading to Scaffold
I begin by asking students to recall the effects of physically weathered rocks from our previous lesson. I want to activate their prior knowledge about physically weathered rocks from wind, water, and temperature. After hearing from a couple of students, I add: "besides changing physically, rocks can change chemically too." I continue explaining to students that many of images they examined in the Odd One Out activity were caused by another kind of process called, chemical weathering. Chemical weathering causes changes to the Earth's surface differently than physical weathering. Chemical weathering still breaks down the rocks and other materials, but causes them to decompose and/or dissolve away rather than in smaller pieces. I share that rain can have chemicals in it because as it falls through the atmosphere it absorbs carbon dioxide from the air and overtime, changes the appearance of a rock.
To further develop their understanding, I play a podcast that highlights key points of chemical weathering. I use this to further scaffold the information since they have not formally learned about composition of rocks and minerals. I provide them with this information to prepare them for their lab activity.
Guided Inquiry Set-Up
I call on a student to read the standards board to the class: "today we will examine how chemical weathering slowly changes Earth's surface by conducting a simulation and making observations." I add on by saying "Our goal is to determine conditions and factors that create the changes similar to the images we saw in odd one out." I tell them they are simulating the effects of rainwater on rocks by using vinegar for rain on chalk to represent a rock. I ask students to set up their interactive notebook with their pre-cut task card and output card.
I move on and review the procedure on the task card with the class and identify the lab rats roles for each part. Then explain, "we are using a chalk to represent a piece of the Earth, a rock, and you are using vinegar to simulate the effects of acid rain on it to observe the effects of chemical weathering." I selected a chalk to represent a rock because the vinegar (acid rain) causes it to breakdown and dissolves parts of it which is what happens to some rocks as they are chemically weathered. The chemical makeup of the chalk changes as it is exposed to the acids in the vinegar. This illustrates how over time acid rain breaks down the certain minerals and dissolves rocks that make up the Earth's surface. It provides a visual model of how chemical weathering causes changes to the Earth's surface.
Guided Inquiry Investigation
I continue with directions "First, you are writing an observation about the chalk before you do anything to it. Be sure to examine its size, shape, texture etc. and record them on your output page table. Then, you are writing a prediction about what you think is going to happen to the chalk as vinegar is applied to it." I continue explaining, "Once your prediction is written, the lab rats' director initiates the procedure, reminds the lab rats' technician to be ready for monitoring and timing of the drops of vinegar, and group members to observe the effects of vinegar on the chalk." I remind them that the vinegar is acting like acid rain on Earth. After each person adds vinegar to the chalk, students are observing and noting the changes on the output page data table." I ask for a thumbs up to check in for understanding of the task.
While students are following through the procedure and activity, I circulate the room, monitor groups, and check in to see if the lab rats technician is completing the timing task and monitoring the amount of drops placed on the chalk.
I am looking to see if students are observing and noting changes the vinegar made to the chalk's size, shape, and appearance. I want them to make the connection to how some materials on Earth's surface like rocks change and/or dissolve as they react with chemicals in the air or water.
After completing the procedure, I project the images from the Odd One Out strategy at the start of the lesson. I want the students to visually make the connections from the chemical weathering simulation and the chemical weathering effects seen on each picture.
Connecting the Investigation to the Real World
I ask students to reflect on what they have learned during the simulation of chemical weathering on the chalk by answering the output card questions. Through these questions, I want the students to make the connection to how minerals and other elements in rocks react to chemicals in acid rain and that these rocks shape, size, and texture become changed.
● How does what you observed with vinegar on the chalk compare to what happens to chemically weathered rocks?
● Using evidence from the activity in connection to land, make a claim about the effects of chemical weathering on the land. Start your statement with the sentence starters: I claim....followed by The evidence I have to support my claim
I want them to use a sentence starter so they practice using good sentence structure and develop well-defined explanations.
I share with my students that they are using the strategy think-pair-share to respond in writing to output questions before pairing for their group discussion. Giving them time to think encourages students to participate with their peers in small groups more confidently by having time to think and write their ideas before engaging in a discussion. They are more willing to participate as they they have something prepared to contribute to the group. In addition, it helps students further develop their conceptual understanding about chemical weathering as they build upon their thinking from listening to other students share their thinking.
While students are working on their thinking part of think pair share, I am walking around and checking in with students. Once finished, I ask the students to share their thinking with group members. I tell the students, "it is ok to disagree with a group member as long as it is done in a respectful manner. As we have in the past, we begin our disagree statements with, I respectfully disagree with _____ because..." With that said, I remind them they need to provide relevant evidence from our investigation or previous lesson. In addition, I tell them to ask questions about the parts they disagree with because it might help them and their peer find clarity.
Once groups have finished discussions, I inform my students our investigation continues tomorrow with reporters from each group presenting to the class. I ask them to be prepared for that by taking the last few minutes of class to wrap up discussions. By informing them of what's ahead tomorrow, I am setting them up to be ready an active participant tomorrow as a reporter or listener.