Read satellite images and before-and-after photos

Grade 9 Social Studies Worksheet - Challenge Me

Circle the best answer.

1. Read this first

   Use this

   Card A. Lake Powell and the Aral Sea (public-domain NASA images, described in words). Lake Powell, 1999 and 2004 (Landsat): in 1999 the water reaches far into the side canyons; by 2004 the side canyons are shorter, and pale, bare canyon walls outline the lake. Aral Sea, 2000 and 2014 (MODIS): in 2000 the lake is already a fraction of its 1960 size, in a northern part and two southern lobes; in 2014 the eastern lobe of the South Aral Sea is gone. Key: Lake Powell: dark blue = water; pale outline = canyon walls once under water. Aral Sea: blue = water; yellow line = the 1960 shoreline. Note: a dam finished in 2005 separates the North Aral Sea from the South Aral Sea. Card B. Two readers (made up). Reader X says: the Aral images show the lake was already shrinking before 2000 and shrank further after. Reader Y says: the images show that the 2005 dam made the eastern lobe disappear.

2. 1.

   Reader Y says the 2005 dam made the eastern lobe disappear. What do the Aral images support, Ari asks?

   • Reader Y is right, since the dam was finished between the two images
   • Reader Y is wrong, since the dam separates the North from the South Aral Sea
   • The lobe is there in 2000 and gone in 2014, the dam in between; no cause is shown
   • Reader X is right, so the dam did nothing to the lake

3. Use this

   Card A. Lake Powell and the Aral Sea (public-domain NASA images, described in words). Lake Powell, 1999 and 2004 (Landsat): in 1999 the water reaches far into the side canyons; by 2004 the side canyons are shorter, and pale, bare canyon walls outline the lake. Aral Sea, 2000 and 2014 (MODIS): in 2000 the lake is already a fraction of its 1960 size, in a northern part and two southern lobes; in 2014 the eastern lobe of the South Aral Sea is gone. Key: Lake Powell: dark blue = water; pale outline = canyon walls once under water. Aral Sea: blue = water; yellow line = the 1960 shoreline. Note: a dam finished in 2005 separates the North Aral Sea from the South Aral Sea.

4. 2.

   A student says Lake Powell changed less than the Aral Sea. What is wrong with comparing the two pairs, Bo asks?

   • The pairs span 5 and 14 years and show different things, so rates cannot be compared
   • The pairs use different colors for water, so nothing compares
   • Nothing: 14 years of change is plainly bigger than 5 years of change
   • They cannot be compared, since Powell is a reservoir and the Aral a natural lake

5. Use this

   Card A. Lake Powell and the Aral Sea (public-domain NASA images, described in words). Lake Powell, 1999 and 2004 (Landsat): in 1999 the water reaches far into the side canyons; by 2004 the side canyons are shorter, and pale, bare canyon walls outline the lake. Aral Sea, 2000 and 2014 (MODIS): in 2000 the lake is already a fraction of its 1960 size, in a northern part and two southern lobes; in 2014 the eastern lobe of the South Aral Sea is gone. Key: Lake Powell: dark blue = water; pale outline = canyon walls once under water. Aral Sea: blue = water; yellow line = the 1960 shoreline. Note: a dam finished in 2005 separates the North Aral Sea from the South Aral Sea. Card C. Pixel sizes, in our words. These Landsat images have pixels about 30 m wide. These MODIS images have pixels about 250 m wide.

6. 3.

   Which feature would be clearer in the 30 m Landsat image than in the 250 m MODIS image, Esme asks?

   • A color difference between water and land, since MODIS cannot show colors
   • A lake 100 km across, since large objects need large pixels
   • A canyon arm about 300 m wide: ten Landsat pixels, barely one MODIS pixel
   • A change over fourteen years, since Landsat has more dates

7. Use this

   Card A. Lake Powell and the Aral Sea (public-domain NASA images, described in words). Lake Powell, 1999 and 2004 (Landsat): in 1999 the water reaches far into the side canyons; by 2004 the side canyons are shorter, and pale, bare canyon walls outline the lake. Aral Sea, 2000 and 2014 (MODIS): in 2000 the lake is already a fraction of its 1960 size, in a northern part and two southern lobes; in 2014 the eastern lobe of the South Aral Sea is gone. Key: Lake Powell: dark blue = water; pale outline = canyon walls once under water. Aral Sea: blue = water; yellow line = the 1960 shoreline. Note: a dam finished in 2005 separates the North Aral Sea from the South Aral Sea.

8. 4.

   In the 2004 Powell image, pale walls outline the lake. What do they support, Jun asks?

   • Water stood higher in 1999 than in 2004; the pale walls were once under water
   • Water stood higher in 2004; the pale walls show the 2004 shoreline
   • The pale walls show how deep the lake was in 2004
   • The walls were bare before 1999, so the outline shows rock that was dry throughout
9. 5.

   Which question can the Aral pair of 2000 and 2014 answer, Luz asks?

   • No question: images fourteen years apart answer nothing about the lobe
   • Whether the eastern lobe existed in each year, but not when it vanished
   • Whether the lobe vanished before or after 2005, using the dam as a marker
   • When in 2005 the lobe vanished, since the dam was finished then
10. 6.

    Milo’s note says: “The Aral Sea had vanished by 2014.” Which fix is right?

    • Leave it: the lake was already a fraction of its 1960 size by 2000, so it had nearly vanished
    • Change it: the North Aral Sea vanished, since the dam separated it, so the north is gone
    • Change it: the Aral Sea vanished by 2005, when the dam was finished, and the image shows it
    • Change it: the 2014 image shows one lobe of the South Aral Sea gone, not the sea
11. 7.

    Noah’s note says: “Pale walls in the 2004 Powell image show the lake dried up.” Which fix is right?

    • Change it: they show the lake rose between 1999 and 2004, leaving the walls exposed
    • Change it: they show a lower level than in 1999, not a dry lake
    • Leave it: bare pale walls mean no water is left in the canyons
    • Change it: they show the 1960 shoreline, as on the Aral Sea

12. Use this

    Card C. Pixel sizes, in our words. These Landsat images have pixels about 30 m wide. These MODIS images have pixels about 250 m wide.

13. 8.

    Pia’s note says: “MODIS images with 250 m pixels can show the five-year change in a 50 m wide side canyon.” Which fix is right?

    • Change it: a 50 m canyon is narrower than one 250 m pixel
    • Change it: MODIS shows the 50 m canyon but not the five-year change
    • Leave it: five years is long enough for any sensor to catch the change
    • Change it: a 250 m pixel shows a 50 m canyon in five pixels

14. Use this

    Card A. Lake Powell and the Aral Sea (public-domain NASA images, described in words). Lake Powell, 1999 and 2004 (Landsat): in 1999 the water reaches far into the side canyons; by 2004 the side canyons are shorter, and pale, bare canyon walls outline the lake. Aral Sea, 2000 and 2014 (MODIS): in 2000 the lake is already a fraction of its 1960 size, in a northern part and two southern lobes; in 2014 the eastern lobe of the South Aral Sea is gone. Key: Lake Powell: dark blue = water; pale outline = canyon walls once under water. Aral Sea: blue = water; yellow line = the 1960 shoreline. Note: a dam finished in 2005 separates the North Aral Sea from the South Aral Sea.

15. 9.

    In the 2014 Aral image, which area was lake in 1960 and is not water now, Ren asks?

    • The area inside the yellow line but not blue
    • The area outside the yellow line, since the 1960 lake lay beyond its shoreline
    • The strip along the 2005 dam, since the dam marks the old shoreline
    • The area inside the blue shapes, since blue marks the 1960 lake

16. Use this

    Card A. Lake Powell and the Aral Sea (public-domain NASA images, described in words). Lake Powell, 1999 and 2004 (Landsat): in 1999 the water reaches far into the side canyons; by 2004 the side canyons are shorter, and pale, bare canyon walls outline the lake. Aral Sea, 2000 and 2014 (MODIS): in 2000 the lake is already a fraction of its 1960 size, in a northern part and two southern lobes; in 2014 the eastern lobe of the South Aral Sea is gone. Key: Lake Powell: dark blue = water; pale outline = canyon walls once under water. Aral Sea: blue = water; yellow line = the 1960 shoreline. Note: a dam finished in 2005 separates the North Aral Sea from the South Aral Sea. Card C. Pixel sizes, in our words. These Landsat images have pixels about 30 m wide. These MODIS images have pixels about 250 m wide.

17. 10.

    A teacher asks which pair gives better evidence of long-term change. What is the best answer, Zee asks?

    • The Aral pair, since its 1960 line adds a baseline from decades earlier
    • Neither, since two dates cannot show change over a long span
    • Powell, since Landsat pixels are smaller and so show change better
    • Powell, since five years apart is closer and so more precise