D2.Geo.8.6-8: Desert Canals and the Growth and Decline of Settlements
In plain English: D2.Geo.8.6-8 is the C3 Framework geography indicator for grades 6-8 that asks students to analyze how the relationships between people and their environment can extend or contract where people settle and how they move. Students use National Park Service, Reclamation and Census sources on canals, dams and the growth of Phoenix in the Arizona desert.
Analyze how relationships between humans and environments extend or contract spatial patterns of settlement and movement.
C3 Framework for Social Studies (NCSS) · Dimension 2: Applying Disciplinary Concepts and Tools · Discipline: Geography · Human Population: Spatial Patterns and Movements · Official standard
Students analyze how the relationship between people and a desert environment has made settlement in central Arizona grow and shrink over a very long time. The ancestral Sonoran Desert people dug irrigation canals from the rivers, which let villages spread far from the riverbanks; later the region lost much of its population. Starting in 1867, newcomers in the Salt River Valley dug canals again, struggled with floods and droughts until many left, and then built a large storage dam. In the twentieth century, Phoenix grew into one of the largest cities in the country.
D2.Geo.8.6-8 uses two key verbs: a relationship with the environment can extend a pattern (people settle or travel farther) or contract it (people pull back or leave). Students apply both verbs to two patterns: settlement (where people live) and movement (where people travel and migrate). Sources are a National Park Service page (Source 1), a Bureau of Reclamation project history (Source 2), U.S. Census Bureau data on Phoenix (Source 3) and NOAA rainfall normals (Source 4).
Learning Objectives
By the end of this lesson, students will be able to:
Define human-environment relationship, settlement pattern and movement pattern, and tell when a pattern is extended or contracted.
Explain how irrigation canals and a storage dam extended settlement in the dry Salt and Gila river valleys.
Explain how environmental problems such as drought, floods and salt in the soil can contract settlement and cause people to leave.
Use population, land area and rainfall data to describe how a desert city's settlement pattern changed.
Prior Knowledge Required
Students should already be comfortable with:
Using maps and other representations to explain relationships between places and changes in their environment D2.Geo.2.6-8
Reading information from charts, graphs and maps and connecting it to a text RH.6-8.7
Dividing to find a rate, such as people per square mile, and rounding
"Phoenix gets about 7 inches of rain in a whole year. That is less than the height of a sheet of notebook paper. How could a large city, or even a farming village, grow in a place like that? Write two ideas."
Collect ideas such as rivers, wells, canals, dams and air conditioning. Circle the ones that change the environment (canals, dams) and the ones that help people live with it (houses that stay cool). Tell students that today they will see people in the same valleys use water to spread out, and also lose ground and leave.
Direct Instruction15-20 minutes
Key terms for D2.Geo.8.6-8 (working definitions)
Term
What it means
Example from this lesson
Human-environment relationship
The ways people depend on, adapt to and change the natural world, and how the natural world affects them
Digging canals to bring river water to fields
Arid
Very dry: a place that gets little rain each year
The Sonoran Desert around Phoenix
Irrigation
Bringing water to crops by canals, ditches or pipes instead of waiting for rain
Canals from the Salt River
Settlement pattern
Where people live and how their homes and towns are spread across the land
Villages along rivers; a city that spreads outward
Movement pattern
Where people travel or migrate, and which way
Families moving into the valley, or leaving it
Extend
Make a pattern larger: people settle in new land or travel to new places
Villages built farther from the rivers
Contract
Make a pattern smaller: people pull back from land or leave a place
A valley losing many of its people
Reservoir and storage dam
A dam holds back a river to form a lake (a reservoir) so water can be saved for dry times
Theodore Roosevelt Dam on the Salt River
Salinization
A build-up of salt in soil, which can happen when irrigation water evaporates and leaves its salts behind; salty soil grows poor crops
Named in Source 1 as one possible cause of decline
Population density
The number of people per square mile (people divided by area)
Phoenix in 1950: about 6,247 people per square mile
Part 1: Look at the land and the water. Show Diagram 1 and Source 4. Rivers are the only dependable water in this region, and Diagram 1 shows that the Salt and Verde rivers meet near Phoenix and flow into the Gila. Ask: if you could only farm where water reaches, where would the villages be? (Along the rivers.) Then ask what would happen to that pattern if people could move water away from the rivers.
Part 2: Extend and contract. Draw a line on the board with arrows pointing outward labeled extend and inward labeled contract. Under it, write settlement and movement. Every event today goes in one of four boxes. Model one: "A village digs a canal and plants fields 5 kilometers from the river" extends settlement.
Part 3: Worked examples. Use Source 3, the Census Bureau data for Phoenix, and Source 4.
Source 3: Phoenix, Arizona, population and land area (U.S. Census Bureau)
Year
Population
Land area (square miles)
1950
106,818
17.1
1960
439,170
187.4
1970
581,562
247.9
1980
789,704
324.0
1990
983,403
419.9
2000 (estimate)
1,323,107
(not given)
2010
1,445,632
(not given)
Source 4: Average yearly precipitation, 1991-2020 (NOAA National Centers for Environmental Information, U.S. Climate Normals)
Weather station
Inches per year
Phoenix Sky Harbor International Airport
7.22
Tucson International Airport
10.61
Source 3 notes: 1950-1990 values are from Census Bureau Working Paper No. 27 (Tables 18-22); 2000 is not a census count: it is the Census Bureau's April 1, 2000 estimates base for the city (an estimate), and 2010 is the 2010 census count. Land area for 2000 and 2010 is not in these tables. Precipitation means rain plus melted snow.
Settlement extends: more people
Use Source 3. How many more people lived in Phoenix in 1960 than in 1950, and about how many times as many?
Result: 439,170 - 106,818 = 332,352 more people. 439,170 / 106,818 = 4.1, so about 4 times as many in ten years.
Settlement extends: more land
Use Source 3. How did the city's land area change from 1950 to 1960?
Result: 187.4 / 17.1 = 11.0, so the city covered about 11 times as much land. The city limits moved outward over farmland and desert: the settled area extended.
Population density
Find Phoenix's population density in 1950 and in 1960.
Result: 1950: 106,818 / 17.1 = 6,247 people per square mile. 1960: 439,170 / 187.4 = 2,343 people per square mile. Density fell even though the population grew, because the city spread out faster than it filled in.
Reading the environment
Use Source 4. How much rain and snowmelt does Phoenix get in a year, in centimeters (1 inch = 2.54 cm)?
Result: 7.22 x 2.54 = 18.3 cm per year, a little less than the length of a new pencil. Farming there depends on river water, not rain.
Teacher tip. Students may think that a bigger city must be more crowded. Example 3 shows the opposite: density can fall while population rises. Ask: "Did the people spread out or squeeze in?"
Guided Practice15 minutes
The first canal builders. Source 1 is from the National Park Service, which manages Casa Grande Ruins National Monument. It uses the name ancestral Sonoran Desert people for the people archeologists call Hohokam; O'odham, Hopi and Zuni people are among their descendants. Read it aloud. Work through paragraph 2 together; paragraphs 1 and 3 are for the quiz and Independent Practice.
1The ancestral Sonoran Desert people discovered that as their villages grew, farm land adjacent to the rivers was becoming scarce. To bring water to land farther away from the rivers, they began to dig canals around 1500 B.C.E., a technique they continued to use for generations. Archeologists have discovered hundreds of miles of prehistoric irrigation canals in the Gila River valley, as well as the Salt River Valley of Phoenix, the Santa Cruz River Valley in Tucson, and on the American Indian reservations of Southern Arizona.
[...]
2Once the idea of irrigation farming took hold, it spread gradually throughout central and southern Arizona. From about 600 to 900 C.E., more villages were established in the Salt and Gila river valleys. Hohokam culture colonists moved up the Verde River valley north of Phoenix, and up the Salt river valley east of Phoenix. They also moved downstream as far west as Gila Bend. Growth of new villages and canal systems also took place along the Santa Cruz river in the Tucson area.
[...]
3During the late 1300’s and early 1400’s, the ancestral Sonoran Desert people suffered a period of widespread depopulation and change. Speculations as to the cause have included drought, floods, disease, invasion, earthquakes, internal strife, and salinization of farmland. Today, several indigenous groups have links to the ancestral people. Their cultural traditions, together with on-going archeology and the continued interest of visitors at Casa Grande Ruins, all combine to keep the legacy of the ancestral Sonoran Desert people alive to this day.
National Park Service, U.S. Department of the Interior, The Ancestral Sonoran Desert People (Source 1, National Park Service, Casa Grande Ruins National Monument) (2024). US government work (17 U.S.C. 105). Source text.
An idea spreads. Prompt: paragraph 2 begins, "Once the idea of irrigation farming took hold, it spread gradually." Is this about settlement, movement or both? Teacher note: both. New villages are settlement; colonists moving to new valleys are movement.
Trace the moves. Prompt: name the places colonists moved to. Find each on Diagram 1. Teacher note: up the Verde River valley north of Phoenix, up the Salt River valley east of Phoenix and downstream as far west as Gila Bend; villages and canals also grew along the Santa Cruz River near Tucson.
Extend or contract? Prompt: did the patterns in paragraph 2 extend or contract? What made it possible? Teacher note: they extended, because canals carried water to new land. The human-environment relationship (using river water) made a larger settlement pattern possible.
Measure it. Prompt: use the scale bar on Diagram 1 to estimate how far Gila Bend is from Phoenix in a straight line. Teacher note: about 89 km; accept 80-100 km.
Independent Practice15 minutes
The second canal builders. Source 2 is from the Bureau of Reclamation, the federal agency that built Theodore Roosevelt Dam. Read it with a partner. Words to know: a diversion dam turns part of a river into a canal; laterals are smaller ditches that branch off a main canal; erratic means changing in ways that are hard to predict.
1Irrigation of the Salt River Valley began about 1867. The riverflow was erratic, varying from a small stream to enormous floods. During years of drought, the supply of water at low river stages was inadequate for the land in cultivation. River flows in excess of immediate needs or canal capacities were lost, due to lack of storage facilities. From 1867 to 1902, a number of diversion dams, canals, and laterals were constructed by private companies or through community effort. Difficulties caused by lack of water storage, inadequate diversion dams, and inequitable water distribution were so critical that many of the settlers left the valley. A committee was named to investigate the feasibility of a water storage system. A reservoir site located 80 miles from Phoenix, where Tonto Creek flowed into the Salt River, seemed the most practical. Such a reservoir would cost from $2 to $5 million. As a territory of the United States, Arizona was prohibited from assuming such a large-scale debt; private investors could not be induced to take on the financial risk necessary to construct the dam. The Salt River Valley Water Users` Association was incorporated on February 9, 1903, for the purpose of furnishing water, power, and drainage for the benefit of approximately 4,800 individual landowners.
2Construction was started on August 24, 1903, and the first water was delivered in 1907. [...]
Bureau of Reclamation, U.S. Department of the Interior, Salt River Project: History (Source 2, Bureau of Reclamation) (2026). US government work (17 U.S.C. 105). Source text.
Task (pairs). (1) Make a two-column chart: extends and contracts. Put at least two events from Source 2 in each column, and label each one settlement or movement. (2) How many years passed between the start of irrigation in the valley and the first water from the new project? (3) Read paragraph 3 of Source 1 on your own. Write one sentence comparing what happened to the ancestral Sonoran Desert people with what happened to the settlers in Source 2.
Look for: extends: canals and diversion dams built from 1867, the reservoir plan, construction from 1903 and first water in 1907; contracts: years of drought and lost floodwater, and "many of the settlers left the valley" (movement out). The gap is 1907 - 1867 = 40 years. Strong comparisons note that in both periods water problems shrank settlement, but the later settlers had a storage dam to try next.
Closure10 minutes
Exit ticket: Draw the extend-contract line from Part 2. Place one event from Source 1 and one from Source 2 on it, and write one sentence explaining the human-environment relationship behind each.
Teacher note on names and perspective: The Park Service page that Source 1 comes from explains why the Park Service now says ancestral Sonoran Desert people: "Hohokam" is an archeologists' word and not the name of a tribe. Use the Park Service's term for the people. Source 1 also says the causes of the decline in the late 1300s and early 1400s are not known for sure; teach them as possibilities, not facts.
Teacher note on scope: water use in Arizona today is a topic of public debate. This lesson stays with documented history and data and does not ask students to take a side on current water policy.
Differentiation Strategies
For Struggling Students
Give the four-box chart (extend or contract, settlement or movement) with one example filled in.
Read Source 2 in two chunks, stopping after the sentence about settlers leaving.
Provide a division template for density: people / square miles = people per square mile.
For Advanced Students
Ask them to compare population density for every year in Source 3 that has a land area and describe the trend.
Ask them to explain why a storage dam helps with both drought and floods, using the phrases in Source 2.
Assessment Guidance
What to Look For
Strong work uses the words extend and contract correctly for both settlement and movement, ties each change to a specific human-environment relationship (canals, storage, drought, flood, salty soil), and uses numbers from Sources 3-4 correctly. Watch for students who call every change extension, who treat the possible causes in Source 1 as proven, or who confuse population with density.
02
Classroom Activities
3 Activities
1
Four-Box Card Sort
15 minPairs
Pairs sort 10 event cards into a four-box grid: extends or contracts, and settlement or movement. Every card comes from Sources 1-3.
The 10 cards
Canals carry river water to land far from the rivers (Source 1)
Colonists move up the Verde River valley north of Phoenix (Source 1)
New villages and canal systems grow along the Santa Cruz River (Source 1)
Widespread depopulation in the late 1300s and early 1400s (Source 1)
Salt builds up in irrigated farmland (Source 1, a possible cause)
Irrigation of the Salt River Valley begins about 1867 (Source 2)
Many settlers leave the valley because of water problems (Source 2)
First water from the new storage project is delivered in 1907 (Source 2)
Phoenix covers 11 times as much land in 1960 as in 1950 (Source 3)
Phoenix's population grows by more than 330,000 from 1950 to 1960 (Source 3)
Steps
Draw a 2 x 2 grid: extends and contracts across the top, settlement and movement down the side.
Place each card and write the human-environment relationship behind it on the card (for example, "using river water" or "salty soil").
Compare with another pair and discuss any card you placed differently.
Answer key and discussion
Extends, settlement: cards 1, 3, 6, 8, 9 and 10. Extends, movement: card 2. Source 3 counts people but does not say where they came from, so card 10 is settlement: part of the growth may be people already living on land the city added. Contracts, settlement: cards 4 and 5. Contracts, movement: card 7. Some cards fit two boxes; for example, card 7 also shrinks settlement. Accept any placement a pair can defend. Ask: which box has the fewest cards, and does that mean contraction was rare, or that fewer sources describe it?
2
Water on the Map
20 minPairs
Pairs mark a printed Diagram 1 to show where water made settlement possible, then measure distances with the scale bar.
Steps
With a blue pencil, shade a band about 1 cm wide on each side of the Salt, Gila and Verde rivers. This band stands for land that canals could reach.
Circle the towns inside the bands.
Use the scale bar to measure the straight-line distance from Phoenix to Theodore Roosevelt Dam and from Phoenix to Camp Verde.
Write one sentence: why would the people of Phoenix depend on a dam that far away?
Answer key
Phoenix to the dam is about 87 km and Phoenix to Camp Verde about 113 km, so accept 80-95 km and 105-120 km. The dam stores water upstream on the Salt River so it can flow down to the valley's canals in dry times.
Discussion
Ask: Tucson is on the Santa Cruz River, shown as an often-dry riverbed. What does that suggest about water for a city there? (Its river cannot be counted on, so other sources of water matter more.) Source 4 shows Tucson gets more rain than Phoenix, but both are arid.
3
Valley Meeting, 1902
20 minGroups of 4
Groups role-play landowners in the Salt River Valley in 1902, the year before the water users' association was formed. Source 2 explains why paying for a storage dam was hard. The roles are invented; the decision is historical.
Role cards
Farmer near the river: has water most years and fears paying for a dam.
Farmer far from the river: loses crops in every drought.
Store owner in town: loses customers each time settlers leave.
Family thinking of leaving: has relatives in California who say there is work there.
Meeting
Each role explains in one minute what a storage dam would mean for them, using Source 2.
The group votes: join an association that pledges its land to repay the cost of a dam, or not.
The group writes two sentences predicting how its choice would extend or contract settlement and movement in the valley.
Debrief
Tell students what happened: the association was formed in 1903, construction began that year and the first water came in 1907 (Source 2). Ask which roles had the most to gain. Score the predictions on reasoning, not on the vote.
03
Diagrams & Visual Aids
2 diagrams
Diagram 1: Rivers, Valleys and Towns of Central and Southern Arizona
Map of Arizona drawn from the U.S. Census Bureau's 2023 state boundary file, in a simple projection (the scale bar is correct near 34°N). River lines join the locations of U.S. Geological Survey streamgages in order along each river, so they are simplified. The Santa Cruz River is dashed because it is often dry; the dotted line joins its lowest gage near Tucson to a gage near Laveen, south of Phoenix. Town points are from the Census Bureau's 2023 Gazetteer. The dam's location is from the Bureau of Reclamation.
Diagram 2: Phoenix Population and Land Area
Bar graphs drawn to scale from Source 3 (U.S. Census Bureau). Panel A: population of the city of Phoenix, 1950-2010, in millions (the 2000 bar is the Census Bureau's April 1, 2000 estimates base, an estimate). Panel B: land area of the city, 1950-1990, in square miles.
04
Homework Assignment
~30 min
D2.Geo.8.6-8 Homework: Spreading Out in the Desert
Directions: Use Sources 1-4 and Diagrams 1-2. Round densities to the nearest whole number and percents to one decimal place. Show your work for every number.
Part 1: Read the Data (Problems 1-3)
Use Source 3. Find Phoenix's population density in 1970 and in 1980. Did the city fill in or spread out between those years? Explain using both density and land area.
Use Source 3. By what percent did Phoenix's population grow from 1980 to 1990, and from 2000 to 2010? In which period did it grow faster?
Use Source 4. How many centimeters of precipitation does Tucson get in a year (1 inch = 2.54 cm)? Then explain why rainfall alone cannot explain where people settled in this region.
Part 2: Extend or Contract? (Problems 4-6)
Use paragraph 1 of Source 1. Explain how the ancestral Sonoran Desert people's relationship with the rivers extended their settlement pattern. Quote the sentence that gives their reason.
Use Source 2. Explain how one environmental problem contracted the movement pattern of the valley's settlers, and how the storage dam was meant to reverse it.
Write a paragraph of 5-7 sentences comparing the two periods of canal building in Sources 1 and 2. Use the words extend and contract, name one human-environment relationship for each period, and use at least one number from Source 3.
Rubric
Criterion
3: Strong
2: Developing
1: Beginning
Calculations
Densities, percents and conversions correct, with work shown
One or two errors
Several errors or no work
Extend and contract
Uses both words correctly for settlement and for movement
Uses the words with one mix-up
Words missing or misused
Human-environment relationship
Names a specific relationship for each change (canals, storage, drought, salt)
Names relationships in general terms
No relationship named
Evidence
Accurate quotation and numbers tied to each claim
Evidence present but loosely tied
No evidence
05
Quiz: 20 Questions
Interactive, with answers
Instructions
Questions 1-5 use Source 1 (National Park Service) in Guided Practice and Questions 6-7 use Source 2 (Bureau of Reclamation) in Independent Practice; paragraph numbers refer to the numbered paragraphs. Questions 8-11 use Sources 3 and 4 in Direct Instruction. Other questions use Diagram 1, the key terms and the activities. Choose an answer to see whether it is right; for short-answer questions, write your answer first and then open the model answer.
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
According to paragraph 1 of Source 1, why did the ancestral Sonoran Desert people begin to dig canals?
Answer: D
D is right. Paragraph 1 says that "as their villages grew, farm land adjacent to the rivers was becoming scarce," so they dug canals "to bring water to land farther away from the rivers." A is not in the source; the canals took water from the rivers. B and C name other uses of canals that the paragraph does not mention.
Question 2 of 20 · Multiple Choice
Paragraph 1 of Source 1 lists river valleys where archeologists have found prehistoric canals. Which valley is NOT on that list?
Answer: C
C is right. Paragraph 1 names the Gila River valley, the Salt River Valley of Phoenix, the Santa Cruz River Valley in Tucson and reservations of southern Arizona. The Verde River valley appears in paragraph 2, as a place colonists moved to, which is why it is easy to confuse.
Question 3 of 20 · Multiple Choice
According to paragraph 2 of Source 1, where were more villages established from about 600 to 900 C.E.?
Answer: A
A is right: "From about 600 to 900 C.E., more villages were established in the Salt and Gila river valleys." B, C and D are places that the paragraph does not mention.
Question 4 of 20 · Multiple Choice
Paragraph 3 of Source 1 lists possible causes of the depopulation in the late 1300s and early 1400s. Which is NOT on the list?
Answer: C
C is right. The list is "drought, floods, disease, invasion, earthquakes, internal strife, and salinization of farmland." A volcanic eruption is not named; a student who picks it may be thinking of earthquakes, which are on the list. A, B and D are all named.
Question 5 of 20 · Multiple Choice
According to paragraph 3 of Source 1, what keeps the legacy of the ancestral Sonoran Desert people alive today?
Answer: D
D is right: the paragraph says their descendants' "cultural traditions, together with on-going archeology and the continued interest of visitors at Casa Grande Ruins, all combine to keep the legacy" alive. A, B and C are not in the paragraph.
Question 6 of 20 · Multiple Choice
According to paragraph 1 of Source 2, what problems were so serious that many settlers left the Salt River Valley?
Answer: B
B is right. Source 2 says "lack of water storage, inadequate diversion dams, and inequitable water distribution were so critical that many of the settlers left the valley." "Inequitable" means unfair. A contradicts the source, which describes drought. C and D are not in the paragraph.
Question 7 of 20 · Multiple Choice
According to paragraph 1 of Source 2, why could the Arizona territory not pay for the storage dam itself?
Answer: A
A is right: "As a territory of the United States, Arizona was prohibited from assuming such a large-scale debt." B contradicts the source, which gives the cost as $2 to $5 million still to be found. C contradicts the many settlers who needed water. D is wrong: the site was 80 miles from Phoenix, where Tonto Creek meets the Salt River.
Question 8 of 20 · Multiple Choice
Use Source 3. What was Phoenix's population density in 1990, to the nearest whole number?
Answer: D
D is right: 983,403 / 419.9 = 2,342 people per square mile. A divides by 4,199 instead of 419.9 (the decimal point moved one place right). C divides by 41.99 (the decimal point moved one place left). B multiplies the area by 1,000 instead of dividing the population by the area.
Question 9 of 20 · Multiple Choice
Use Source 3. How many more people lived in Phoenix in 1990 than in 1970?
Answer: B
B is right: 983,403 - 581,562 = 401,841. A adds the two numbers. C is the growth from 1980 to 1990 (983,403 - 789,704). D is the growth from 1970 to 1980 (789,704 - 581,562).
Question 10 of 20 · Multiple Choice
Use Source 3. By how many square miles did Phoenix's land area grow from 1970 to 1990?
Answer: C
C is right: 419.9 - 247.9 = 172.0 square miles. A is the 1970-1980 increase (324.0 - 247.9). B is the 1980-1990 increase (419.9 - 324.0). D subtracts the 1950 area from 1990 (419.9 - 17.1).
Question 11 of 20 · Multiple Choice
Use Source 4. How many more inches of precipitation does Tucson get in a year than Phoenix?
Answer: B
B is right: 10.61 - 7.22 = 3.39 inches. A adds the two values. C divides them (10.61 / 7.22 = 1.47), which says how many times as much, not how much more. D is Tucson's total, not the difference.
Question 12 of 20 · Multiple Choice
Source 1 says canals began around 1500 B.C.E. and depopulation came in the late 1300s and early 1400s C.E. About how long did people farm with canals in these valleys before the decline?
Answer: A
A is right: B.C.E. years count down to year 1 and C.E. years count up, so from 1500 B.C.E. to 1400 C.E. is about 1,500 + 1,400 = 2,900 years (2,899 exactly, since there is no year 0). B subtracts 1,500 - 1,400 as if both dates were in the same era. C counts only the B.C.E. part, and D counts only the C.E. part.
Question 13 of 20 · Multiple Choice
Which event is an example of a human-environment relationship that CONTRACTS a movement pattern?
Answer: C
C is right: crop failure in a drought (environment) makes families leave (a movement out, so the area people move into shrinks). A and B extend settlement by bringing or saving water. D extends the city's settlement pattern.
Question 14 of 20 · Multiple Choice
On Diagram 1, in which direction is Theodore Roosevelt Dam from Phoenix?
Answer: B
B is right: the dam is about 0.9 degrees of longitude east of Phoenix and about 0.1 degrees north, so it lies east and slightly north. A and C point away from the dam. D ignores that the dam is much farther east than north.
Question 15 of 20 · Short Answer
Explain how the canals of the ancestral Sonoran Desert people extended both their settlement pattern and their movement pattern. Use paragraphs 1 and 2 of Source 1.
Model answer: Canals brought river water "to land farther away from the rivers," so villages could be built and farmed away from the riverbanks, which extended settlement. As the idea of irrigation spread, colonists moved up the Verde and Salt valleys and downstream to Gila Bend, which extended their movement into new valleys. Rubric: 1 point for settlement, 1 point for movement, 1 point for evidence from each paragraph.
Question 16 of 20 · Short Answer
Paragraph 3 of Source 1 lists several possible causes of the decline. Choose one that is a human-environment relationship and explain how it could contract settlement.
Model answer: Salinization of farmland is a human-environment relationship, because it can happen when people irrigate fields and the water evaporates, leaving salt behind. Salty soil grows poor crops, so families could no longer feed themselves there and would leave or move to fewer places, which contracts settlement. Drought or floods are also acceptable if the answer explains how people's use of the rivers was affected. Rubric: 1 point for a correct cause, 1 point for the human-environment link, 1 point for explaining contraction.
Question 17 of 20 · Short Answer
Use Source 2. Explain how the Theodore Roosevelt Dam was meant to change the relationship between the settlers and the Salt River.
Model answer: Before the dam, the river's flow was erratic: in drought years there was too little water, and in flood years extra water was lost because there was no storage. A storage dam would hold floodwater in a reservoir and release it in dry years, so the settlers would depend less on the river's ups and downs and could stay and farm more land. Rubric: 1 point for the problem before, 1 point for how storage works, 1 point for the effect on settlement.
Question 18 of 20 · Short Answer
Use Source 3. Phoenix's population grew from 1950 to 1960 but its density fell. Explain how both can be true, and what this shows about its settlement pattern.
Model answer: The population grew about 4 times, but the land area grew about 11 times, so there were fewer people for each square mile. The city was spreading outward over new land faster than it was filling in, so its settlement pattern was extending. Rubric: 1 point for comparing the two growth rates, 1 point for explaining density, 1 point for naming the extended pattern.
Question 19 of 20 · Short Answer
Compare the two periods of canal building in Sources 1 and 2. Give one way they were alike and one way they were different.
Model answer: Alike: in both periods people used river water to extend settlement into a dry valley, and in both periods water problems made people leave. Different: the later settlers had a storage dam built with federal help, while Source 1 does not describe storage dams for the earlier people. Rubric: 1 point for a likeness, 1 point for a difference, 1 point for evidence from both sources.
Question 20 of 20 · Short Answer
Name one human-environment relationship today that could extend or contract where people live in your own region. Explain which it would do and why.
Model answer: In a coastal town, rising flood risk could contract settlement if people move away from the lowest streets. In a town with a new reservoir, water storage could extend settlement onto land that was too dry before. Any example works if it names the environment, what people do, and whether the pattern extends or contracts. Rubric: 1 point for a relationship, 1 point for extend or contract, 1 point for a clear reason. Students should describe effects, not argue for a policy.
0 of 20 answered · 0 correct
06
Frequently Asked Questions
10 Questions
What does D2.Geo.8.6-8 mean?
D2.Geo.8.6-8 asks middle school students to analyze how the ways people use and adapt to their environment can make settlement and movement spread out (extend) or shrink (contract). Students look at both where people live and where they travel or migrate.
What is an example of D2.Geo.8.6-8 in real life?
Irrigation in a desert is a clear example. Canals and dams let people farm and build far from a river, which extends settlement; drought, floods or salty soil can make people leave, which contracts it. This lesson follows both in the desert valleys around Phoenix, Arizona.
What is the difference between settlement and movement patterns?
A settlement pattern is where people live and how their homes and towns are spread over the land. A movement pattern is where people travel or migrate and which way. A change in one often causes a change in the other.
Does contract always mean people left?
Not always. A pattern contracts when it gets smaller: people may leave, crowd into fewer places, or stop using land they once farmed. Leaving is one kind of contraction, often shown in a movement pattern.
Why does the lesson say ancestral Sonoran Desert people instead of Hohokam?
The National Park Service page used in the lesson explains that Hohokam is an archeologists' term, not the name of a tribe, and that the descendants of these people do not use it. The Park Service now uses ancestral Sonoran Desert people for the people and Hohokam only for archeology, and the lesson follows that practice.
Where do the numbers on this page come from?
Population and land area come from the U.S. Census Bureau (Working Paper No. 27 for 1950-1990, and later census files). Precipitation comes from NOAA's 1991-2020 U.S. Climate Normals. The map uses Census Bureau boundaries and places, U.S. Geological Survey streamgage locations and Bureau of Reclamation dam data.
What mistakes do students make with this standard?
Common ones are calling every change "extend," forgetting movement patterns, treating possible causes as proven facts, and confusing population with population density. Asking "bigger or smaller, and for living or for moving?" helps.
Is this lesson about current water debates?
No. Water use in the Southwest is debated today, but this lesson uses documented history and data to teach a geographic idea. Teachers can mention that the debate exists without asking students to take a position.
How does D2.Geo.8.6-8 connect to other geography standards?
It builds on D2.Geo.2.6-8, which uses maps and images to explain changes in environmental characteristics, and it pairs with D2.Geo.7.6-8 on how technology changes connections between places. In high school, D2.Geo.8.9-12 shifts to how economic activities and political decisions shape urban, suburban and rural patterns.
How long does this lesson take?
About 60-70 minutes, with three optional activities of 15-20 minutes each. The card sort works as a quick review on a second day, and the 1902 valley meeting can stand alone as a discussion lesson.
07
Related Standards
5 standards
These standards connect to D2.Geo.8.6-8: prerequisites to review first, parallel standards at the same level, and next steps that build on it.
Before this lesson
D2.Geo.2.6-8Prerequisite
Use maps and other representations to explain places, regions and environmental change
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.
