D2.Geo.2.6-8: How Location Shaped Environmental Change at Mount St. Helens
In plain English: D2.Geo.2.6-8 is the C3 Framework geography indicator for grades 6-8 that asks students to use maps, satellite images, photographs and other representations, such as graphs and tables, to explain how the location of a place or region is related to the changes in its environment.
Use maps, satellite images, photographs, and other representations to explain relationships between the locations of places and regions, and changes in their environmental characteristics.
C3 Framework for Social Studies (NCSS) · Dimension 2: Applying Disciplinary Concepts and Tools · Discipline: Geography · Geographic Representations: Spatial Views of the World · Official standard
D2.Geo.2.6-8 asks students to use maps, satellite images, photographs and other representations to explain how the location of a place is related to changes in its environment. This lesson uses one event that changed a whole region in a day: the eruption of Mount St. Helens, Washington, on May 18, 1980. Students read a map of where places lie compared with the volcano, an SVHS summary, with short quotations, of NASA's description of a 37-year series of Landsat satellite images, two U.S. Geological Survey photographs (described in words, with links so the teacher can show them), and a USGS data table and graph of ash depth.
Each representation shows a different relationship. Direction mattered: the blast went north and the wind carried ash east. Distance mattered: ash was thick near the volcano and thin far away. Position in the landscape mattered: places down river valleys were hit by mudflows. And location shaped recovery: according to NASA, the part of the blast zone farthest from the volcano turned green first. Students practice writing a relationship statement that links a location to a change and names the representation that shows it.
Learning Objectives
By the end of this lesson, students will be able to:
Describe a place's location by distance and direction from another place
Tell what a map, a satellite image, a photograph and a graph or table can each show about environmental change, and what each cannot show
Explain how direction, distance and position in the landscape were related to the changes at and around Mount St. Helens
Use evidence from more than one representation to explain why some places recovered sooner than others
Write a relationship statement that links location to environmental change and cites its evidence
Prior Knowledge Required
Students should already be comfortable with:
Constructing and reading maps with a key, scale bar and north arrow D2.Geo.1.6-8
Reading bar graphs and tables
Using cardinal and intermediate directions (northeast, southwest)
"A volcano erupts. Picture four places: a forest right next to it on the north side, a town 80 miles to the east, a farm in a river valley that starts on the volcano's slopes, and a city 50 miles to the southwest. Which place do you think changed the most? Which changed the least? What about each place's location makes you think so?"
Record guesses in two columns: distance reasons and direction or landscape reasons. Students will test these guesses with real evidence. Tell them the places in the prompt are like real places near Mount St. Helens.
Direct Instruction15 minutes
Part 1: Location words.Absolute location is an exact address or latitude and longitude. Relative location describes a place compared with another place, such as "82 miles east-northeast of the volcano." A region is an area with something in common, such as the blast zone, the area where the volcano's sideways explosion knocked down or killed the forest. Environmental characteristics are natural features such as forests, rivers, lakes, soil and landforms.
Part 2: Four kinds of representations. A map shows where places are and how far apart they are. A satellite image is a picture of Earth taken from space; the U.S. Landsat satellites have photographed the same places again and again since 1972, so a series of images can show change over time. Some Landsat images are false-color: colors are swapped so that, for example, healthy plants look red. A photograph taken on the ground or from a plane shows what a place looks like up close at one moment. Other representations include graphs, tables and diagrams that turn measurements into numbers.
Part 3: The relationship statement. Use the frame: "Places that were [location: distance, direction or landscape position] changed by [change], as shown by [representation]." A strong statement names a location, a change and the evidence.
Relative location from a map
On Diagram 1, Yakima is east-northeast of Mount St. Helens. Its straight-line distance, computed from the two places' coordinates, is about 82 miles.
Result: Relative location: about 82 miles east-northeast of the volcano. On the 50-mile scale bar, that is a little more than 1.6 bar lengths.
Reading a data table
The USGS table gives the summit's height as 9,677 feet before the eruption and 8,363 feet after.
Result: 9,677 - 8,363 = 1,314 feet of mountaintop removed, which matches the USGS figure of 1,314 feet.
Comparing two representations
A photograph shows bare, gray ground with no trees in front of the crater. A map shows that this ground lies on the north side of the volcano, inside the 17-mile circle.
Result: Relationship: the ground close to the volcano on its north side lost its forest, as shown by the photograph (what it looks like) and the map (where it is).
What a representation cannot show
A student uses only Diagram 2, the ash-depth graph, to describe the eruption's effects.
Result: The graph shows how ash depth changed with distance downwind, but not which direction "downwind" was, and not the blast or the mudflows. A map or a written source is needed for those.
Selected measurements of the May 18, 1980 eruption (real data: U.S. Geological Survey Fact Sheet 036-00, "Summary of May 18, 1980 Eruption of Mount St. Helens Volcano")
Covered 230 square miles; reached 17 miles northwest of the crater
Landslide
Buried 14 miles of the North Fork Toutle River valley to an average depth of 150 feet (up to 600 feet)
Blast deposit depth
From about 3 feet at the volcano to less than 1 inch at the blast edge
Trees blown down
4 billion board feet of timber
Ash fall depth
10 inches at 10 miles downwind; 1 inch at 60 miles downwind; 1/2 inch at 300 miles downwind
Lahars (mudflows)
Damaged 27 bridges and nearly 200 homes
Guided Practice15 minutes
Read the map and Source 2 together. Project Diagram 1. Students find the volcano, the 17-mile circle and the arrow for the ash. Then read Source 2, a USGS fact sheet. Words to know: a flank is the side of a mountain; lateral means sideways; a lahar is a volcanic mudflow; prevailing winds are the winds that usually blow from one direction in a place. Work through the steps below, writing one relationship statement after each.
1Within 15 to 20 seconds of a magnitude 5.1 earthquake at 8:32 a.m., the volcano's bulge and summit slid away in a huge landslide - the largest on Earth in recorded history. The landslide depressurized the volcano's magma system, triggering powerful explosions that ripped through the sliding debris. Rocks, ash, volcanic gas, and steam were blasted upward and outward to the north. This lateral blast of hot material accelerated to at least 300 miles per hour, then slowed as the rocks and ash fell to the ground and spread away from the volcano; several people escaping the blast on its western edge were able to keep ahead of the advancing cloud by driving 65 to 100 miles an hour! The blast cloud traveled as far as 17 miles northward from the volcano and the landslide traveled about 14 miles west down the North Fork Toutle River.
2[...] Over the course of the day, prevailing winds blew 520 million tons of ash eastward across the United States and caused complete darkness in Spokane, Washington, 250 miles from the volcano.
3During the first few minutes of this eruption, parts of the blast cloud surged over the newly formed crater rim and down the west, south, and east sides of the volcano. The hot rocks and gas quickly melted some of the snow and ice capping the volcano, creating surges of water that eroded and mixed with loose rock debris to form volcanic mudflows (lahars). Several lahars poured down the volcano into river valleys, ripping trees from their roots and destroying roads and bridges.
Steve Brantley and Bobbie Myers, U.S. Geological Survey, Fact Sheet 036-00, Mount St. Helens: From the 1980 Eruption to 2000, the May 18 eruption (Source 2) (2000). US government work (17 U.S.C. 105). Source text.
Direction. Prompt: in paragraph 1, which way did the blast go, and which way did the landslide go? Teacher note: the blast went "upward and outward to the north" and traveled "as far as 17 miles northward"; the landslide traveled "about 14 miles west down the North Fork Toutle River."
Wind. Prompt: paragraph 2 says the winds blew the ash which way? Find a city on Diagram 1 that lies in that direction and is far away. Teacher note: Spokane, which the USGS says was 250 miles from the volcano; measured in a straight line from the coordinates it is about 246 miles.
Landscape position. Prompt: paragraph 3 says where the lahars went. Why would a place in a river valley that starts on the volcano be at risk even if it is far from the crater? Teacher note: mudflows follow valleys downhill, the way water does.
Write a class statement. Model: "Places north of the volcano and within about 17 miles lost their forests, as shown by Source 2 and the circle on Diagram 1."
Independent Practice20 minutes
Satellite images and photographs. Source 1 is an SVHS summary, with short quotations, of a NASA Earth Observatory article that describes a series of Landsat images of the volcano taken between 1979 and 2016. Source 3 describes two USGS photographs in words; if possible, project the NASA images and the photos from the USGS fact sheet at the links in the source list. Words to know: debris is broken pieces of rock and wood; a quadrant is one quarter of an area; conspicuously means very noticeably.
1This is an SVHS summary, written for this page, of a NASA Earth Observatory article about a series of Landsat satellite images of Mount St. Helens taken between 1979 and 2016. The words in quotation marks are NASA's own. The series shows the blast zone just before the eruption and in the years of recovery after it. The older images are false-color, with plants shown in red. NASA explains that this is "because earlier Landsat satellites could not 'see' blue light," and a photo-like image needs red, green and blue light.
2On May 18, 1980, the explosion went upward and outward to the north. According to NASA, the blast "spread volcanic debris (gray in the images)" over 230 square miles (600 square kilometers) and blew down 4 billion board-feet of timber. Through the image series, a raft of dead trees drifts around Spirit Lake. Around the southern half of the mountain, volcanic mudflows (lahars) poured down rivers and gullies.
3NASA reports that "the first noticeable recovery (late 1980s) takes place in the northwestern quadrant of the blast zone, farthest from the volcano." About ten years later, in the late 1990s, the land east of Spirit Lake is "considerably greener." By 2016, the end of the series, the only area beyond the mountain's own slopes that still looks "conspicuously bare at the scale of these images" is the Pumice Plain.
SVHS, summarizing NASA Earth Observatory, World of Change: Mount St. Helens (first published 2010), The Landsat image series of Mount St. Helens: an SVHS summary with short quotations from NASA (Source 1) (2026). Original passage written for this page (an SVHS summary; the short quotations are credited to NASA Earth Observatory). Source text.
1Photograph A (black and white, taken on May 18, 1980): A huge, lumpy column of gray ash and gas rises from the top of the mountain and fills most of the picture. It rises far higher than the top of the mountain. Below it, the mountain's slopes are streaked with snow and dark rock.
2Photograph B (color, taken after the eruption from the north side of the volcano): The mountain no longer has a pointed top. Its middle is a wide, open gap, the crater, with steep walls on the left and right that are still covered in snow. In front of the mountain, the ground is a broad, flat, gray-brown plain with no trees, crossed by shallow gullies. The USGS caption says the crater is "horseshoe-shaped" and faces north, and that a lava dome steams inside it.
SVHS, describing two U.S. Geological Survey photographs by Austin Post and Lyn Topinka, printed in Fact Sheet 036-00, Two USGS photographs of Mount St. Helens: an SVHS description written for this page (Source 3) (2026). Original passage written for this page. Source text.
Change chart. Students make a chart with three columns: Place or zone, How it changed, Which representation shows it. They fill in at least five rows using Sources 1-3, Diagrams 1 and 2 and the data table, then write two relationship statements: one about the eruption day and one about the recovery that followed. Diagram 2 turns the ash-depth row of the data table into a bar graph.
Closure10 minutes
Back to the warm-up. Revisit the four places in the warm-up prompt. Which guesses held up, and which representation proved or changed each one?
Exit ticket (index card): "Name one representation from today and one relationship between location and change that it shows. Then name one thing that representation could not show you."
Teacher note: the eruption killed 57 people, according to the same USGS fact sheet, and many students will want to talk about the human cost. Treat it with care. The lesson's focus is the environment, but the USGS figures on bridges and homes in the data table can open a short discussion of how environmental change affects people.
Differentiation Strategies
For Struggling Students
Give a word bank for directions and a compass rose printed on Diagram 1
Provide the change chart with the first column filled in: blast zone north of the volcano, North Fork Toutle valley, towns far to the east, northwest edge of the blast zone, Pumice Plain
Read Source 1 aloud and pause after each sentence that names a place
For Advanced Students
Use Diagram 2 to estimate how many times thinner the ash was at 300 miles than at 10 miles, and explain why the graph's distance axis is not to scale
Open the NASA image series and write captions for three of the years that name a place and a change
Compare the USGS phrase "17 miles northward" with the table's "17 miles northwest" and explain how both can describe one area that spread north and northwest of the crater
Assessment Guidance
What to Look For
Strong answers give relative locations with both distance and direction, connect each change to a specific location, and name the representation that shows it. Strong answers also say what a representation cannot show, for example that a single photograph shows one moment and one view. Watch for statements that list changes without any location, for confusion between "downwind" and "north," and for students who treat the 17-mile circle on Diagram 1 as the shape of the blast zone, which it is not.
02
Classroom Activities
3 Activities
1
Where Would It Change? Location Cards
15 minPairs
Pairs get 8 cards, each describing an invented spot near a volcano like Mount St. Helens on its eruption day, with winds from the west. Using the USGS data table and Source 2 as a guide, they predict the main change at each spot (blast, thick ash, thin ash, mudflow, little or none) and write the location clue that supports the prediction.
The 8 Location Cards (invented spots)
A forest 6 miles north of the crater
A meadow 12 miles south of the crater, on a ridge above the valleys
A ranch 70 miles east of the volcano
A bridge over a river 30 miles downstream, in a valley that begins on the volcano's slopes
A town 45 miles west of the volcano, on a hill away from any river
A lake 8 miles north of the crater
A wheat farm 280 miles east of the volcano
A campground 9 miles east of the crater
Answer Key
1 and 6: blast (north and within 17 miles). 8: thick ash (close and downwind; the USGS reports 10 inches at 10 miles downwind). 3: ash about an inch or less (the table gives 1 inch at 60 miles). 7: thin ash (about 1/2 inch at 300 miles). 4: mudflow (downstream in a valley from the volcano). 2 and 5: little or none from blast or ash, because they are upwind or off to the side and away from valleys; accept "some risk" for card 2 if the pair explains that blast surges also went down the south side, as Source 2 paragraph 3 says.
Discussion
Ask: which card was hardest, and which location clue (distance, direction or landscape) decided it?
2
Reading a Satellite Image Series
20 minGroups of 3
Groups use Source 1, and the NASA image series if it can be projected, to track how three zones changed between 1979 and 2016. This is the main satellite-image task.
Change Over Time Chart
Rows: (1) the northwest part of the blast zone, (2) the land east of Spirit Lake, (3) the Pumice Plain. Columns: Before 1980; Late 1980s; Late 1990s; End of the series (2016). In each box, write "forest," "bare," "greening" or "green," then write one sentence explaining the order in which the zones recovered.
What Students Should Find
Source 1 paragraph 3 says the first recovery came in "the northwestern quadrant of the blast zone, farthest from the volcano" in the late 1980s, the land east of Spirit Lake turned "considerably greener" in the late 1990s, and the Pumice Plain still looked "conspicuously bare" at the end of the series. The relationship: recovery came first where the land was farthest from the volcano.
Modification: No Projector
Groups fill the chart from Source 1 alone, then discuss what a satellite picture would add that the words cannot.
3
Representation Relay
15 minFour groups, rotating
Four stations, one per representation: Diagram 1 (map), Source 1 (satellite images), Source 3 (photographs) and Diagram 2 with the data table (other representations). Groups spend about 3 minutes at each.
At Each Station
One relationship between location and change that this representation shows
One thing it cannot show
Which other station fills that gap
Wrap-Up
Each group reports the gap it found most important. Build a class chart: map = where; satellite series = change over time across a whole region; photograph = what it looks like up close at one moment; graph or table = how much.
Variation: Local Change
Students pick a place near school that has changed (a new road, a cleared lot, a flooded field) and list which of the four representations would best show the change and why.
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Diagrams & Visual Aids
2 diagrams
Diagram 1: Where Places Lie Compared With Mount St. Helens
Drawn to scale. The volcano's location comes from the U.S. Geological Survey's volcano list (46.2° N, 122.18° W); city locations come from the U.S. Census Bureau's 2023 Gazetteer, and state outlines are simplified from the Census Bureau's 2023 cartographic boundary file. The dashed circle marks every point 17 miles from the volcano, the farthest distance the USGS reports for the blast; the blast itself spread only to the north, so the circle is a distance guide, not the blast zone. The arrow shows the general direction the prevailing winds carried the ash on May 18, 1980, as described in Source 2.
Diagram 2: Ash Depth and Distance Downwind
Bar graph of the three ash-fall depths in the USGS Fact Sheet 036-00 summary table: 10 inches at 10 miles downwind (ash and pumice), 1 inch at 60 miles and 1/2 inch at 300 miles. Bar heights are to scale; the three distances are spaced evenly, not to scale.
04
Homework Assignment
~30 min
D2.Geo.2.6-8 Homework: The Eruption of Mount Tarnell
Directions: Mount Tarnell is an invented volcano, and all its data are made up for this homework. Use the facts below for every problem.
Invented facts: Mount Tarnell erupts on a day when the wind blows from the west. Five places: North Camp, 6 miles north; Pellow, a town 8 miles east; Hollin, a town 45 miles east; Quarry Flats, 25 miles west on high ground; Marsh Fork, a village 20 miles south, beside a river whose valley begins on the volcano's slopes. Measured ash depth (invented): North Camp 3 inches, Pellow 7 inches, Hollin 1.5 inches, Quarry Flats none, Marsh Fork 1/2 inch. Satellite image description (invented): before the eruption, a green forest covers every side of the mountain. One month after, the north side is gray for about 10 miles, a gray streak runs down the river valley to Marsh Fork, and the east side is pale gray. Photograph description (invented): a photo taken in Marsh Fork shows a mud line about 4 feet up the walls of houses near the river, and clean walls on houses up the hill.
Part 1: Locations and Representations (Problems 1-3)
Draw a simple map with Mount Tarnell in the center and the five places at their distances and directions. Use a scale of 1 cm = 5 miles. How many centimeters from the volcano will you place Hollin, and how many for Marsh Fork?
Make a bar graph of the ash depth at the five places, ordered from west to east (Quarry Flats, then the places on or near the line through the volcano, then Pellow and Hollin). Which place has the thickest ash, and what about its location explains it?
For each representation (your map, your graph, the satellite description, the photograph description), name one thing it shows about the eruption that the others do not.
Part 2: Explaining Relationships (Problems 4-6)
Pellow is 8 miles east and North Camp is 6 miles north, yet Pellow got more than twice as much ash. Explain this using the wind and both locations. How many times as much ash did Pellow get?
Marsh Fork is south of the volcano, not downwind, but it changed a lot. Use the satellite and photograph descriptions to explain how its location caused the change. Why were the houses up the hill not muddy?
Write three relationship statements, one each about direction, distance and landscape position, using the frame "Places that were ___ changed by ___, as shown by ___." Then predict which place will turn green again first in later satellite images, and explain your prediction.
Rubric
Criterion
Full Credit (2 pts)
Partial Credit (1 pt)
No Credit (0 pts)
Locates Places
Map to scale with correct distances and directions
Map with small errors
Map missing or places misplaced
Uses Representations
Graph correct and each representation's strength named
Graph or strengths partly correct
Representations not used
Explains Relationships
Each explanation links a location (direction, distance or landscape) to a change
Some links made
Changes listed without locations
Uses Evidence
Cites the invented facts and descriptions, including numbers
Some evidence
No evidence
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Quiz: 20 Questions
Interactive, with answers
Instructions
Questions 1, 2 and 13 use Diagram 1 in Guided Practice. Questions 3-5 and 14 use Source 1, and questions 6 and 7 use Source 3, both in Independent Practice. Questions 10-12 use Source 2 in Guided Practice. Questions 8, 9 and 13 use Diagram 2 and the data table in Direct Instruction. Choose the best answer, then check it.
Multiple choice: pick an option to check it. Short answer: write your answer, then reveal the model answer.
0 of 20 answered · 0 correct
Question 1 of 20 · Multiple Choice
Use Diagram 1. Which best describes Portland's location compared with Mount St. Helens?
Answer: C
Portland is below and a little to the left of the volcano, about one scale-bar length away: about 50 miles south-southwest (the coordinates give 51 miles). Option B reverses the direction; option A describes Yakima; option D doubles the distance.
Question 2 of 20 · Multiple Choice
Use the scale bar on Diagram 1. About how far is Seattle from Mount St. Helens in a straight line?
Answer: D
Seattle is about two scale-bar lengths north of the volcano, so about 100 miles (the coordinates give 98). 50 miles (B) counts only one bar length; 250 miles (C) is the USGS distance to Spokane.
Question 3 of 20 · Multiple Choice
According to paragraph 1 of Source 1, why are plants shown in red in the older Landsat images?
Answer: B
Paragraph 1 says the older images are false-color "because earlier Landsat satellites could not 'see' blue light." Option A takes the color literally; options C and D invent meanings the source does not give (it says debris is gray).
Question 4 of 20 · Multiple Choice
According to paragraph 2 of Source 1, what does the color gray show in the Landsat images?
Answer: C
Paragraph 2 says the blast "spread volcanic debris (gray in the images)." Healthy plants (A) are red in the older false-color images; snow (B) and lake water (D) are not what the source says gray marks.
Question 5 of 20 · Multiple Choice
What can a series of Landsat images taken over many years show that a single ground photograph cannot?
Answer: A
A series shows the same large area again and again, so it reveals change over time across a region. A ground photograph shows one view up close at one moment (B); neither kind of image gives the summit height in feet (C, which comes from the data table) or sound and temperature (D).
Question 6 of 20 · Multiple Choice
In Source 3, which detail of Photograph B shows that the forest on the north side of the volcano was destroyed?
Answer: D
The photo was taken from the north, and the ground in front of the mountain is bare, with no trees. The gap (B) shows the summit was destroyed, not the forest; snow (A) and clouds (C) say nothing about the forest.
Question 7 of 20 · Multiple Choice
Which is a limit of Photograph A (the ash column on May 18) as evidence of the eruption's effects?
Answer: A
A single photograph freezes one moment and one view, so it cannot show where the ash fell or how deep it was. It is a real USGS photograph (B is false), it was taken on the eruption day (C is false), and it cannot measure distance (D).
Question 8 of 20 · Multiple Choice
Use Diagram 2. How many times as deep was the ash at 10 miles downwind as at 60 miles downwind?
Answer: C
10 inches ÷ 1 inch = 10 times. 20 times (D) compares 10 miles with 300 miles (10 ÷ 0.5); 2 times (A) compares 60 miles with 300 miles (1 ÷ 0.5); 5 times (B) does not match any pair of bars.
Question 9 of 20 · Multiple Choice
The USGS table says the landslide buried the valley to an average depth of 150 feet and up to 600 feet in places. How many times as deep was the deepest spot as the average?
Answer: B
600 ÷ 150 = 4. Option C subtracts (600 - 150 = 450) instead of dividing; option D divides 600 by 100; option A is a miscount.
Question 10 of 20 · Multiple Choice
Which relationship statement is best supported by paragraph 3 of Source 2?
Answer: B
Paragraph 3 says lahars "poured down the volcano into river valleys." Option A mixes up the blast direction with the ash direction (Diagram 2 says nothing about north); option C contradicts paragraph 1, where the blast went north; option D confuses the ash, which went east, with the mudflows.
Question 11 of 20 · Multiple Choice
According to Source 2, why did places east of Mount St. Helens receive ash on May 18?
Answer: C
Paragraph 2 says "prevailing winds blew 520 million tons of ash eastward." The blast went north (A) and the landslide went west (B), as paragraph 1 says; lahars (D) were mudflows in valleys, not the way ash spread.
Question 12 of 20 · Multiple Choice
According to paragraph 1 of Source 2, what happened 15 to 20 seconds before the volcano's bulge and summit slid away?
Answer: A
Paragraph 1 says the slide came "Within 15 to 20 seconds of a magnitude 5.1 earthquake." The ash column (B) came after the blast; the source says nothing about the winds changing (C); the lava dome (D) grew in the years after 1980.
Question 13 of 20 · Multiple Choice
Moses Lake is about 152 miles from the volcano, in the direction the ash traveled. Using only Diagram 2, what is the most reasonable estimate of the ash depth there?
Answer: D
152 miles lies between the 60-mile bar (1 inch) and the 300-mile bar (1/2 inch), so the depth is most likely between them. Option A is deeper than at 10 miles; option B belongs to places between 10 and 60 miles; option C ignores that the place is downwind. This is an estimate from the graph alone; real ash depths varied from place to place.
Question 14 of 20 · Multiple Choice
NASA says the first recovery came in the part of the blast zone farthest from the volcano. Which location reason best explains this?
Answer: B
The data show deposits thinning with distance (blast deposits went from about 3 feet near the volcano to less than 1 inch at the blast edge), so the edge was less damaged and plants came back first. The other options give reasons the sources do not support.
Question 15 of 20 · Short Answer
Write two relationship statements about the eruption day, one about direction and one about distance. Each must name a location, a change and the representation that shows it.
Model answer: Direction: "Places north of the volcano lost their forests to the lateral blast, as shown by Source 2 paragraph 1 and the bare ground in Photograph B." Distance: "Places closer to the volcano downwind got deeper ash, as shown by Diagram 2: 10 inches at 10 miles but 1/2 inch at 300 miles." Rubric: 2 points per statement with location, change and representation.
Question 16 of 20 · Short Answer
The dashed circle on Diagram 1 has a radius of 17 miles. Find its area (use 3.14 for π), and find about what fraction of that area the blast covered, using the USGS figure of 230 square miles.
Area = 3.14 × 17 × 17 = 3.14 × 289 ≈ 907 square miles. 230 ÷ 907 ≈ 0.25, so the blast covered only about one quarter of the circle. The circle is a distance guide, not the shape of the blast zone, which spread only to the north. Rubric: 1 point for the area, 1 for the comparison, 1 for the conclusion.
Question 17 of 20 · Short Answer
Compare what Photograph B (Source 3) and the Landsat series (Source 1) each tell you about the land north of the volcano.
Model answer: Photograph B shows the land up close at one moment: a flat, gray-brown plain with no trees in front of the crater. The Landsat series shows the whole blast zone from above over many years, including the order in which parts of it turned green again. The photo gives detail; the satellite series gives area and change over time. Rubric: 1 point for each source, 1 point for the comparison.
Question 18 of 20 · Short Answer
Use paragraph 3 of Source 2 and the USGS data table. Explain why a home's position in the landscape (beside a river in a valley or up on a hill) mattered on May 18, 1980.
Model answer: Paragraph 3 says hot rock and gas melted snow and ice, and the lahars "poured down the volcano into river valleys, ripping trees from their roots and destroying roads and bridges." Mudflows follow valleys downhill, so homes beside rivers that start on the volcano were in their path, while homes on higher ground were not. The table shows the cost: lahars damaged 27 bridges and nearly 200 homes. Rubric: 1 point for the valley link, 1 for the quotation, 1 for the data.
Question 19 of 20 · Short Answer
A scientist wants to know whether the forest about 15 miles north of the volcano has grown back. Which representation would you choose, and why? Name one weakness of your choice.
Model answer: A new Landsat satellite image compared with the 1979 image, because it covers the whole area and can be compared with earlier images in the same series. Weakness: it can miss small plants and young trees, because Source 1 describes what is visible "at the scale of these images." A ground photograph or a visit can fill that gap. Rubric: 1 point for a sensible choice, 1 for the reason, 1 for the weakness.
Question 20 of 20 · Short Answer
Diagram 2 has only three bars. Give one reason a reader should be careful using it to judge the ash depth at a town 60 miles north of the volcano.
Model answer: The graph measures distance downwind, and on May 18 the wind blew the ash east. A town 60 miles north was not downwind, so it probably got far less than 1 inch. The graph shows distance but not direction, so it must be read with a map. Rubric: 1 point for noticing the direction problem, 1 point for linking it to the map or the wind.
0 of 20 answered · 0 correct
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Frequently Asked Questions
10 Questions
What does D2.Geo.2.6-8 mean?
D2.Geo.2.6-8 asks middle school students to use maps, satellite images, photographs and other representations to explain how where a place is relates to how its environment changes. The full text is "Use maps, satellite images, photographs, and other representations to explain relationships between the locations of places and regions, and changes in their environmental characteristics."
Do students have to use all four kinds of representations?
Yes, the standard names maps, satellite images, photographs and "other representations," so a full unit uses all four. This lesson pairs each with a source: a scale map, an SVHS summary of NASA's description of Landsat images, two USGS photographs and a USGS data table and graph.
How can I teach satellite images and photographs if my class cannot see them?
Project them from the federal sites when you can, and use written descriptions when you cannot. NASA's Earth Observatory and the USGS publish the Mount St. Helens images free, and the written sources in this lesson describe what the images show, so every task works on paper too.
What is a false-color satellite image?
It is an image in which the colors are not what your eye would see; in the older Landsat images of Mount St. Helens, for example, plants look red. Students should always read an image's key or caption before interpreting its colors.
Why use Mount St. Helens for D2.Geo.2.6-8?
Because one event shows several location relationships at once. Direction, distance and position in the landscape each explain a different change, and NASA's long series of satellite images shows how recovery followed a spatial pattern too.
What is a relationship statement?
It is a sentence that links a location to a change and names the evidence. The frame used here is "Places that were ___ changed by ___, as shown by ___." It keeps students from listing changes without saying where they happened.
Is this a science lesson or a geography lesson?
It is a geography lesson that uses Earth science content. The focus is on reading representations and explaining patterns across space, which is the geography skill. Science teachers covering volcanoes and Earth's surface can pair it with their own lessons.
How is D2.Geo.2.6-8 different from D2.Geo.1.6-8?
D2.Geo.1.6-8 is about constructing maps to show patterns; D2.Geo.2.6-8 is about using many kinds of representations to explain how location relates to change. In this lesson students mostly read and compare representations rather than build maps.
What mistakes do students often make with these representations?
A frequent one is listing changes without saying where they happened. Another is taking the colors of a false-color image literally.
What does the high school version add?
D2.Geo.2.9-12 keeps the same four kinds of representations but asks students to explain how locations relate to political, cultural and economic dynamics, not only environmental change.
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Related Standards
5 standards
These standards connect to D2.Geo.2.6-8: prerequisites to review first, parallel standards at the same level, and next steps that build on it.
Before this lesson
D2.Geo.1.6-8Prerequisite
Construct maps to represent and explain cultural and environmental patterns
Standard text: National Council for the Social Studies (NCSS), The College, Career, and Civic Life (C3) Framework for Social Studies State Standards: Guidance for Enhancing the Rigor of K-12 Civics, Economics, Geography, and History (Silver Spring, MD: NCSS, 2013). NCSS was not involved in the production of this lesson and does not endorse it.
