IC Lessons Weathering
This is lesson 2 of 5 in this IC
A. Title of this lesson: Mechanical weathering – Salt and Chalk Lab
B. Summary of this lesson
This lesson models mechanical weathering, students will mechanically
“weather” pieces of chalk. Students will use salt as an abrasive to scrape off
small particles from the chalk (“rock”).
C. Objective(s)/Learning Goal(s)/ Key Student Learning(s) of this lesson
1. Students will create a simple model of mechanical weathering to
demonstrate the abrasion process on rock.
2. Students will build group process skills and participate in constructive
science discourse.
3. Students will observe and then reflect on this lab, and be able to express
their thinking in a Claim/Evidence/Reasoning format as an exit ticket.
D. Teacher Background Knowledge for this lesson
Students often confuse weathering and erosion because people use these
terms interchangeably. Weathering involves two processes, chemical and
physical, that breaks large rocks into smaller fragments. Weathering may lead
to erosion which is the removal of fragments from one area to another.
“Weathering” may also confuse students because it does not mean that it’s
caused by weather itself.
Depending on your textbook, mechanical or physical weathering may be used
to describe the processes by which rock is broken into smaller pieces. The text
may omit chemical change leading students to partial understanding of
weathering.
E. Prior knowledge that students need to understand this lesson - with an assessment to
determine what they already know (if appropriate).
1) Teach and practice “Claim-Evidence-Reasoning” format
2) Review safety rules with students; salt should not be eaten, thrown, or
put into eyes, etc.
Created by Elizabeth Brooking (West Contra Costa USD), Sarah Nash (Mt. Diablo USD), and Elisa Peters (Mt.
Diablo USD)
F. Standards covered in this lesson
Current California Science Standards
Grade 6 Shaping Earth's Surface
6.2: Topography is reshaped by the weathering of rock and soil and
by the transportation and deposition of sediment.
NGSS
Cross-Cutting Concepts:
Scale, Proportion, and Quantity
Phenomena that can be observed at one scale may not be
observable at another scale. (MS-LS1-1)
Disciplinary Core Ideas:
MS-ESS2-1. Develop a model to describe the cycling of Earth’s
materials and the flow of energy that drives this process.
MS-ESS2-2. Construct an explanation based on evidence for how
geoscience processes have changed Earth’s surface at varying time
and spatial scales.
MS-ESS2.C: The Roles of Water in Earth’s Surface Processes
Water’s movements—both on the land and underground—cause
weathering and erosion, which change the land’s surface features and
create underground formations. (MS-ESS2Develop a model to describe unobservable mechanisms. (MS-ESS2-4)
Science and Engineering Practices
Developing and Using Models
Develop and use a model to describe phenomena. (MS-ESS2-6)
Develop a model to describe unobservable mechanisms. (MS-ESS2-4)
Engaging in Argument from Evidence
Use an oral and written argument supported by empirical evidence
and scientific reasoning to support or refute an explanation or a
model for a phenomenon or a solution to a problem. (MS-LS1-4)
CCSS
Writing:
Created by Elizabeth Brooking (West Contra Costa USD), Sarah Nash (Mt. Diablo USD), and Elisa Peters (Mt.
Diablo USD)
CCSS.ELA-Literacy.W.6.1 Write arguments to support claims with
clear reasons and relevant evidence
Speaking and Listening:
CCCSS SL.6.1 Engage effectively in a range of collaborative discussions.
Presentation of Knowledge and Ideas:
SL 6.4 – Present claims and findings emphasizing points in a focused,
coherent manner with relevant evidence, sound valid reasoning, and
well-chosen details…
G. Suggested time to complete this lesson: 30 minutes
H. Materials Used in this lesson typed in a bulleted list with quantities (e.g., 10 beakers; water –
2 liters)
Each Student – copy of Salt & Chalk Mechanical Weathering worksheet
Set-up for Table Group of four students
 Tray to hold materials
 1 clear plastic cup (8 oz. cup works well) FILLED WITH
 1/2 cup salt (regular table salt)
 1 piece of colored sidewalk chalk
 Timer (one for each group)
I. Materials Prep for this lesson
Technology (if possible)
 Project copy of the Salt & Chalk Mechanical Weathering worksheet using
PowerPoint slide or document camera.
Set materials out on a tray for each work group
 Fill each plastic cup with about ½ cup of salt
 Put in one piece of colored sidewalk chalk into the salt in the cup
 Timer
For each student:
Created by Elizabeth Brooking (West Contra Costa USD), Sarah Nash (Mt. Diablo USD), and Elisa Peters (Mt.
Diablo USD)
 Salt & Chalk Mechanical Weathering worksheet
J. Lesson Plan – detailed, numbered step-by-step plans.
1. Set out trays and worksheets
2. Ask students to predict: (Read with students from the worksheet)
“What will happen to a piece of colored sidewalk chalk if we mix it with
salt for four minutes? What will happen to the salt? Underline your
choices and then explain your answers.”
3. Point on your projected copy of the Salt & Chalk Mechanical Weathering
worksheet, point to where the students will make their prediction and read
with them:
“The chalk will [change shape/change size/stay the same]
The salt will [change color/stay white]”
4. Scan over the class to make sure that they circle a prediction in each
statement.
5. Ask students to explain their reasons for choosing that prediction in the
“Explain” section.
6. After students are finished with their explanations, start the lab:
A. Read the procedures on the worksheet with the students, and check
for their understanding and completion:
B. Draw a picture on the lab sheet of your chalk’s shape in the box titled:
Chalk before the experiment
C. Put your piece of chalk into the cup of salt, and stir carefully with it
for 4 minutes (each student stirs for one minute).
D. If you do not have timers for each group, call out one minute time
increments, and make sure that students take turns stirring.
Created by Elizabeth Brooking (West Contra Costa USD), Sarah Nash (Mt. Diablo USD), and Elisa Peters (Mt.
Diablo USD)
E. After four minutes, have students STOP.
F. Ask student teams to discuss what happened.
7. Formative Assessment- Students complete the Salt & Chalk Mechanical
Weathering worksheet
A. Each student writes down observations on their lab sheet under
“Observations”
B. Each student draws a picture of the chalk in the box titled “Chalk After
the Experiment”
8. Analysis of Data: Based on your data, answer the following question:
What happened to the chalk when it was stirred into salt? Write your
answer in C-E-R format:
9. Help students as needed. Ask them to:
Revisit their prediction and to correct if needed, and then rewrite their
claim on the lines on the worksheet.
Claim:
“The chalk will [change shape/change size/stay the same]
The salt will [change color/stay white]”
The claim is a statement that sums the important point learned from
the experiment.
Evidence:
Students describe what they saw
Evidence is data from the lab that supports the claim
Reasoning:
Students write
Reasoning must explicitly tie the claim and the evidence, and
should describe the scientific principles. Reasoning may describe part
of the procedure.
K. Vocabulary words – key vocabulary words that are targeted or taught as part of the lesson.
Created by Elizabeth Brooking (West Contra Costa USD), Sarah Nash (Mt. Diablo USD), and Elisa Peters (Mt.
Diablo USD)
(Understanding these words is essential for students to understand the key concepts of this
lesson.)






Claim
Evidence
Reasoning
Weathering
Abrade/abrasion
Sediments
L. Potential Pitfalls for: a. student understanding; b. laboratory mishaps and common procedural
errors; c. academic vocabulary issues, etc.
Student misconceptions/Possible Pitfalls:
Misconceptions: Students may think that rocks are just the size they are, and
don’t change in size. Alternatively, they may thing that rocks “grow” to get
bigger, and “shrink” as they get smaller.
Pitfalls: After creating and observing this model activity, students may conclude
that weathering is quick and easy, because materials like chalk do abrade and
weather so easily, even with salt. In addition, some rocks weather much faster
than others, and environmental factors can speed up rates. Make sure that
students understand relative timeframes for geologic change as they relate to
weathering of rock. Pictures from your textbook may prove helpful (i.e., a
gravestone dated from a few hundred years ago may reveal the relative speed
of weathering of that type of rock.) Rates of weathering will be addressed in
Lesson 3.
M. Differentiation: Modifications for English Learners, advanced learners, struggling learners, etc.
Sentence stems:
If language support is needed, you may supply the sentence frame:
The chalk will………because it will/is………………………………………..
The salt will……………because it will/is……………………………………
Students needing more support:
Created by Elizabeth Brooking (West Contra Costa USD), Sarah Nash (Mt. Diablo USD), and Elisa Peters (Mt.
Diablo USD)
 Create a word wall of vocabulary to describe what the students will do
and notice
 Create more sentence frames for discussion and writing purposes
 Post safety reminders
 Write/post/say instructions step by step
Advanced Learners:
 Students can design variations on lab, and repeat at home or in class
 As time permits, use colored chalk for chalk layering art project, using
small jars.
N. Please list all worksheets used in this lesson.
Salt & Chalk Mechanical Weathering worksheet (See attached)
O. Please list all assessments that require a separate sheet.
N/A
P. Photos/Illustrations: N/A
Q. Other Resources
What is sidewalk chalk made of? Gypsum (not calcium carbonate)
http://epod.usra.edu/blog/2009/10/sidewalk-chalk-and-the-calciumcycle.html
Summary of Claim-Evidence-Reasoning
http://www.escofcentralohio.org/Achievement/Documents/Science%20CE
R%20Handout.pdf
Created by Elizabeth Brooking (West Contra Costa USD), Sarah Nash (Mt. Diablo USD), and Elisa Peters (Mt.
Diablo USD)
Name:_____________________________________________ Date: ________________ Period: ______
Salt & Chalk Mechanical Weathering
Predict: What will happen to a piece of colored sidewalk chalk if we mix it with salt
for four minutes? What will happen to the salt? Underline your choices and then
explain your answers.
The chalk will [ change shape/change size/stay the same]
The salt will [ change color/stay white]
Explain:
Materials:
 1 clear plastic cup
 1 piece of colored sidewalk chalk
 1/2 cup salt
 Timer
Student Jobs (assigned by seat number):
1. Materials manager
2. Recorder
3. Reporter
4. Team leader/time keeper
Procedure:
1. Materials managers get materials
2. Draw a picture on the lab sheet of the chalk’s shape.
3. Put the piece of chalk in and stir carefully for 4 minutes (each student stirs for
one minute).
4. Write down observations on the lab sheet and draw a picture about what
happened to the chalk and salt.
5. CLEAN-UP
- Pour out used salt into large bins
- Refill cups with 1/2 cup salt
- Get a new piece of chalk for the next group
- Place all materials onto your tray
- Return tray to designated area
Created by Elizabeth Brooking (West Contra Costa USD), Sarah Nash (Mt. Diablo USD), and Elisa Peters (Mt.
Diablo USD)
Lab Sheet:
Pictures about what happened:
Chalk before the experiment:
Chalk after the experiment:
Observations:
Observations:___________________________________________________________________
________________________________________________________________________________
________________________________________________________________________________
________________________________________________________________________________
________________________________________________________________________________
_____________________________________
_________________________________________________________________________
Analysis of Data: Based on your data, answer the following question:
What happens to chalk when it is stirred with salt? Write your answer in Cl-Ev-R
format:
Claim:
Evidence:
Reasoning:
Created by Elizabeth Brooking (West Contra Costa USD), Sarah Nash (Mt. Diablo USD), and Elisa Peters (Mt.
Diablo USD)