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Grade Level: 7-8
Purpose: To identify the types of rocks and minerals
found in various regions of the state.
Suggested Goals: Students will be able to identify common
rocks and minerals that are found in a specific region of the state through
the analysis of samples of sediments from local ponds, streams, or rivers.
Objectives: As a result of this lesson, students will
be able to:
- Classify sediments based on their physical characteristics, such as
size, shape, and color.
- Identify and describe rocks and minerals that are common to their
region of the state.
Time Required: 2 - 3 class periods
Group Size: Individually or by working in teams of 2-3
students.
Background: The exposure of rocks to the forces of wind,
rain, snow, and ice at the earth's surface breaks them down into smaller
particles. The particles are transported by wind, water, and gravity and
eventually deposited as sediments in or near streams and rivers. By analyzing
the types of rocks found in sediment samples, students can identify the
types of rocks and minerals available in their region of the state.
Materials/Preparation:
- Samples of conglomerate (or other sedimentary rocks)
- Classroom display set of Illinois rocks and minerals [Kit available
from the Illinois State Geological Survey.]
- Rock and mineral identification books
- Access to ISM Geology Online and other geology sites
- Copies of Sediment Sleuth worksheets (printed on card stock, if possible)
- White glue (Elmer’s or similar brand)
For each group:
- 1 sample of sediment obtained from local streams or rivers (use the
small
snack-sized Ziploc bags or small plastic cups and label with location)
- Egg cartons (or 10-12 small plastic cups) for each group
- Toothpick
- Tweezer
- Hand lenses
- Magnets
NOTE: If the students are familiar with the acid test to identify a carbonate,
you may also provide vinegar (or weak HCl acid) and safety goggles.
Skills: Students will need to be able to sort objects
by developing a method of classification. Students will also need to be
able to use identification guides or online resources.
Procedure:
- Ask the students to use a hand lens to examine the conglomerate.
Create a list of observations on the chalkboard. Students should be
able to observe that the sample consists of small pebbles of different
sizes, colors, and textures. Point out that the pebbles are sediments
that have been cemented together.
- Ask the question, "Where do sediments come from?" Students
should be able to demonstrate a basic understanding of the process
of weathering and erosion as outlined in the background section. If
your students do not have an understanding of the process, provide
additional activities exploring weathering and erosion before attempting
this lab.
- Distribute the samples of sediments (sand, soil, and pebbles) and
other materials for the lab. Explain that the sediment samples were
obtained from local streams and rivers. If possible, have the students
bring in their own samples and use a permanent marker to label the
location of each sample.
- Instruct the students to use the egg carton (or small cups) to sort
their sediment samples into categories based on color, shape, and
other physical characteristics using the equipment provided. Students
should have at least one full class period for sorting the sediment
samples.
- After the students have sorted the samples, challenge them to identify
the pebbles by comparing the pieces in each group to the sample rocks
available in a classroom display set, the ISM Geology Online collection,
or an identification guide.
- Once all the rocks have been identified, provide glue to adhere
the samples to the Sediment Sleuths worksheet. Each type of sediment
should be glued in the center of a magnifying glass. The students
should also glue a representative sample of the sediment in the My
Sediments box and indicate the location where the sample was obtained.
- Allow time for the students to research each type of rock or mineral
and complete the name and description sections on the worksheet. Descriptions
may include physical characteristics, mineral composition, classification,
and common uses.
Extensions:
- Contact teachers in other regions of the state and ask that they
have their students do the Sediment Sleuth investigation. Through
the use of e-mail or other communication tools, allow the students
to discuss the results of their investigations. If this is not possible,
request a sample of sediment from the school and allow time for your
students to do the lab again. Mark the locations of the schools on
a map and challenge your students to create a summary report of the
rocks and minerals for a specific region. Students can also use Excel
to create spreadsheets and graphs for the summary report.
- Have the students research the rock cycle as well as the geologic
history of the state using geologic maps, online resources, and other
reference materials. Challenge the students to create a story, cartoon,
or poster about the history of the sediments in the sample and their
journey through the rock cycle.
- Create sediment bottles with the leftover sediment samples to explore
the birth of sedimentary rocks. Have each student bring in one clear
plastic bottle (1 liter or smaller) and provide samples of sediments
containing pebbles, sand, and soil. Allow the students to choose their
own mixture ratio, but caution them not to fill the bottle more than
halfway with sediments. You can also add two to three tablespoons
of Epsom salt to the mixture to help the sediments cement together.
Let the students observe the bottles for 10-15 minutes and make a
list of all their observations as they move the bottle around. After
time is up, discuss the observations and relate to the process of
sedimentary rock formation. Throughout the next few weeks, have students
record their observations of the sediments in the bottles. This activity
may also be used during a unit on weathering and erosion.
Assessment: Assessment for this activity should be based
on the student’s ability to sort the sediments into various categories
and identify the rocks based on the resources available. The Sediment
Sleuths worksheet may be used as a tool to determine if the lesson objectives
have been met.
Print Resources:
- Educational Series 5: Guide to Rocks and Minerals of Illinois
Published by the Illinois State Geological Survey, 1971
- Eyewitness Handbooks: Rocks and Minerals
By Chris Pellant, ISBN# 1-56458-033-4
- Golden Guide: Rocks and Minerals
ISBN #0-307-24499-7
Web Resources:
Setting: Classroom and computer lab with Internet access
State Science Standards:
- 12.E.3a: Analyze and explain large-scale dynamic forces, events
and processes that affect the Earth’s land, water and atmospheric
systems.
- 12.E.3b: Describe interactions between solid earth, oceans,
atmosphere and organisms that have resulted in ongoing changes of Earth.
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