Download 2-1 Classroom Investigations, 5th Grade

PLC 2-1 Grade 5 Investigation –Weathering
Background
Weathering of earth materials is the process by which forces and materials change the physical and chemical
character of rocks near the surface of the Earth. The processes can be classified as:
1. Mechanical weathering – breaking down or crushing of rocks into smaller pieces (e.g., freezing and
thawing, sand carried by wind or water weathering rock).
2. Chemical weathering – breaking down of rock by dissolving by water, exposure to carbon dioxide, water
vapor, and oxygen to form new chemical compounds (e.g., rusting, acid solutions such as acid rain).
3. Erosion – movement of rocks and rock particles by streams, wave action, or glaciers. Most eroded rock
particles are at least partially weathered, but rock can be eroded before it has weathered at all.
The Earth’s surface is constantly changing. Some changes happen very slowly over long periods of time,
such as weathering, erosion, and uplift. Time is the critical component of this ongoing and constant
change.
Exploration:
Students should explore the various rocks before formulating questions to investigate. Students should
formulate hypothesis for the investigation.
Pre-Activity Discussion:
1. Class discussion should focus on students’ experiences with rocks and hardness of rocks.
2. The discussion should provide students with opportunities to share their understanding of the difference
between weathering and erosion. If the students have not developed this understanding, this aspect of the
discussion should come after the activity.
3. Student should be able to share their understanding that rocks are made of minerals and smaller rocks.
4. The teacher should conduct a discussion with sufficient wait time to allow students to reveal their
understanding of rocks, weathering and erosion.
5. The teacher should apply concepts of “Talk and Argument” and extending thinking as described in chapter 5
of RSS. The teacher should focus on assessing student understanding of the concepts and student
understanding of the difference between weathering and erosion.
6. The teachers should be sure to engage students in understanding about variables and the control of variables
when investigating the rocks.
7. Discussion questions might include:
a. What is the difference between weathering and erosion?
b. How does the acidity of the rain affect the rate of weathering?
c. What evidence do you have to support that claim?
Starting Procedure:
1. Obtain 3 to 4 small rock samples of similar size for each rock type (e.g., sandstone, limestone, granite).
2. Clean each of the rocks with water to remove debris and dirt (under tap or in bucket of clean water).
3. After cleaning each rock, observe carefully using a magnifying glass. Draw pictures of the rocks.
4. Now place one rock for each type in various solutions of a) water b) vinegar c) carbonated water.
5. Observe after leaving them in the solution, after 1 hour and again over 3-5 days, look for signs of change.
Investigating Independent Variables:
1. Vary the concentration of the vinegar.
2. Vary the amount of time that one rock type is exposed to the three liquids.
3. Design and investigate an independent variable.
Question 1: What are the differences between weathering and erosion?
Question 2: What in nature is similar to the vinegar solution?
Question 3: What are some warranted inferences that can be made about the shape of the sand particles?
Question 4: How does weathering relate to understanding of chemical change?
Conclusions/Inferences:
Evidence:
Teacher Notes:
 The discussion should focus on students revealing their understanding of the attributes of the rocks and
weathering and erosion. Discuss their understanding of chemical change and the evidence that chemical
change has occurred. Relate the weathering of individual rocks to the changes of land forms. Use
discussion to address students understanding the role of time in the weathering process.
 It is important to provide time for exploring (playing) the tools and the sand to prepare for an investigation.
 The outcome of the investigation should include better understanding of: weathering, example of
chemical change, relate weather of rocks to changes in landforms, the independent variable and controls in
an investigation.
EXAMPLES:
 How is weathering and erosion different and how do they work together?
 How does the weathering of individual rocks relate to the weathering and erosion of landforms?
 How does chemical change relate to weathering?
 What is the role of time in the weathering process?
Standard Operating Procedures:
 Vinegar and water should be clearly labeled and placed on tables in different corners of the room.
 Magnifying glasses and plastic cups should be placed on two tables separate from the samples.
 Provide trays and paper towels or paper plates.
 Encourage students to label the samples.
 Have students explore the rocks before doing the investigation
Utah Science Core Curriculum
Standard 2: Students will understand that volcanoes, earthquakes, uplift, weathering, and erosion reshape
Earth's surface.
Objective 1: Describe how weathering and erosion change Earth’s surface.
a. Identify the objects, processes, or forces that weather and erode Earth’s surface (e.g., ice, plants, animals,
abrasion, gravity, water, wind).
b. Describe how geological features (e.g., valleys, canyons, buttes, arches) are changed through erosion (e.g.,
waves, wind, glaciers, gravity, running water).
c. Explain the relationship between time and specific geological changes.
Objective 3: Relate the building up and breaking down of Earth’s surface over time to the various physical
land features.
a. Explain how layers of exposed rock, such as those observed in the Grand Canyon, are the result of natural
processes acting over long periods of time.
b. Describe the role of deposition in the processes that change Earth’s surface.
c. Use a time line to identify the sequence and time required for building and breaking down of geologic
features on Earth.
d. Describe and justify how the surface of Earth would appear if there were no mountain uplift, weathering,
or erosion.
Materials per group:
 Various rocks (sand stone, limestone, and
 4 Large, clear plastic cups
one or two harder rocks) of about 3-4 cm in
 Magnifying glass
diameter (about the size of a ping pong ball
 Vinegar
 Large plastic cups – Clear works best
 Carbonated water (club soda, or sparkling
 Paper plates or trays with paper towels
water)