Read layered maps the way GIS does: overlay and find the pattern

Grade 9 Social Studies Worksheet - Challenge Me

Circle the best answer.

1. Read this first

   Use this

   Card F (made up for practice). Marlow's flood map in 2010 and in 2020. 2010: 40 homes; the flood zone is a strip along Mill Creek, and 6 homes lie inside it. 2020: 52 homes; the zone was redrawn wider after new measurements, and 11 homes lie inside the 2020 zone; 8 of the 52 homes lie inside the old 2010 strip. The 2020 zone includes the old 2010 strip. Key: shading = flood zone; small square = home. Note: a GIS overlay counts the homes where the layers overlap.

2. 1.

   Noah compares Marlow's homes in the flood zone in 2010 and 2020 on Card F. What are the two shares?

   • About 15% in 2010 and 27% in 2020, because 11 of 40 was the count of homes in 2010
   • 15% in 2010 (6 of 40) and about 21% in 2020 (11 of 52)
   • 15% in 2010 and about 28% in 2020, because 11 more homes in the zone is 11 added to the 2010 figure of 15%
   • 15% in 2010 and about 15% in 2020, because 8 of the 52 homes in 2020 are inside the old strip
3. 2.

   Ari asks how much of the rise in the share came from new homes alone. Using the old 2010 strip on the 2020 homes, what is the share?

   • About 31% (8 + 8 of 52), because the old-strip homes count once for 2010 and again for 2020
   • About 20% (8 of 40), because 8 is the number of homes in the old strip and 40 is the 2010 base
   • About 15.4% (8 of 52), barely above 15.0%, so new building alone moved the share very little
   • About 21% (11 of 52), because the new homes are the reason the 2020 share is up

4. Use this

   Card F (made up for practice). Marlow's flood map in 2010 and in 2020. 2010: 40 homes; the flood zone is a strip along Mill Creek, and 6 homes lie inside it. 2020: 52 homes; the zone was redrawn wider after new measurements, and 11 homes lie inside the 2020 zone; 8 of the 52 homes lie inside the old 2010 strip. The 2020 zone includes the old 2010 strip. Key: shading = flood zone; small square = home. Note: a GIS overlay counts the homes where the layers overlap. Card H (made up for practice). Two readings of Card F. Reading X: "The share of homes in the flood zone rose because people kept building in risky places." Reading Y: "The share rose because the zone was redrawn wider."

5. 3.

   Luz checks Reading X (building in risky places) and Reading Y (zone redrawn) against Card F. Which statement holds?

   • Y alone explains it, because the old-strip share did not change and so building played no part
   • Both contribute, but Y more: new homes lifted the share by about 0.4 points and the redrawn zone by about 5.8
   • X explains it, since 11 homes now lie in the zone against 6 before and the new homes were built in the zone
   • Neither can be tested with Card F, because it gives counts of homes and not the reasons people built where they did

6. Use this

   Card F (made up for practice). Marlow's flood map in 2010 and in 2020. 2010: 40 homes; the flood zone is a strip along Mill Creek, and 6 homes lie inside it. 2020: 52 homes; the zone was redrawn wider after new measurements, and 11 homes lie inside the 2020 zone; 8 of the 52 homes lie inside the old 2010 strip. The 2020 zone includes the old 2010 strip. Key: shading = flood zone; small square = home. Note: a GIS overlay counts the homes where the layers overlap.

7. 4.

   Tala counts what the redrawn zone added in 2020. How many homes are inside the 2020 zone but outside the old 2010 strip?

   • Twelve homes, the 52 homes in 2020 minus the 40 homes counted in 2010
   • Five homes, the 11 in the 2020 zone minus the 6 that were in the zone in 2010
   • Nineteen homes, the 11 in the 2020 zone plus the 8 in the old strip, because OR adds the two layers
   • Three homes, the 11 inside the 2020 zone minus the 8 that were already inside the old strip

8. Use this

   Card F (made up for practice). Marlow's flood map in 2010 and in 2020. 2010: 40 homes; the flood zone is a strip along Mill Creek, and 6 homes lie inside it. 2020: 52 homes; the zone was redrawn wider after new measurements, and 11 homes lie inside the 2020 zone; 8 of the 52 homes lie inside the old 2010 strip. The 2020 zone includes the old 2010 strip. Key: shading = flood zone; small square = home. Note: a GIS overlay counts the homes where the layers overlap. Card G (made up for practice). Marlow's roads and services in 2020. Three roads: Mill Road, Oak Road and Ridge Road. Mill Road and Oak Road cross the 2020 flood zone at bridges; Ridge Road does not. The clinic stands on Ridge Road. Of the 11 homes inside the zone, 7 stand on Mill Road or Oak Road and 4 stand on a side street that joins Oak Road inside the zone. Key: shading = flood zone; line = road; cross = clinic.

9. 5.

   Pia runs: inside the 2020 flood zone AND on Mill Road or Oak Road. What share of the 52 homes does it keep?

   • About 64% (7 of 11), since the query keeps homes in the zone
   • About 35% (18 of 52), because OR adds the 11 zone homes and the 7 on those roads
   • About 13.5% (7 of 52), the zone homes that stand on Mill Road or Oak Road
   • About 21% (11 of 52), since the 11 zone homes are on a road that crosses the zone

10. Use this

    Card G (made up for practice). Marlow's roads and services in 2020. Three roads: Mill Road, Oak Road and Ridge Road. Mill Road and Oak Road cross the 2020 flood zone at bridges; Ridge Road does not. The clinic stands on Ridge Road. Of the 11 homes inside the zone, 7 stand on Mill Road or Oak Road and 4 stand on a side street that joins Oak Road inside the zone. Key: shading = flood zone; line = road; cross = clinic.

11. 6.

    Bo reads Card G: the clinic is on Ridge Road, which does not cross the zone. What follows for the 11 zone homes?

    • The clinic is in the zone, since the flood layer covers the road layer on the map
    • The 11 homes can reach the clinic without crossing the zone, since the clinic is on a road that avoids it
    • Nothing about the clinic can be said, because the layers show roads and not buildings
    • Ridge Road avoids the zone, but the card gives no route from each home to it, so access is not shown
12. 7.

    Milo runs: inside the 2020 flood zone AND NOT on Mill Road or Oak Road. Which homes does Card G leave?

    • The 4 homes on the side street that joins Oak Road inside the zone
    • The 7 homes on Mill Road or Oak Road, because the NOT part keeps those roads and removes the others
    • The 11 homes in the zone, since the query removes roads from the map and not homes from the zone
    • No homes, because the homes in the zone stand on a road that crosses the zone at a bridge

13. Use this

    Card C. Egypt: water, farms and people, drawn as see-through layers on one base map. Egypt's land area is about 1 million km². Layer 1 (water): the Nile flows north through Egypt to its delta on the Mediterranean Sea. Layer 2 (farmland): cultivated land, about 35,000 km², or about 3.5% of Egypt's land, lies along the Nile and in the delta; the rest is desert. Layer 3 (people): almost all of Egypt's people live in the Nile Valley and Delta, which cover only about 5% of the country. Key: blue = river; green = cultivated land; dark shading = where most people live; tan = desert. Note: nine governorates of Lower Egypt lie in the delta, and ten of Upper Egypt line the Nile from Cairo south to Aswan.

14. 8.

    Kira writes: "Egypt's farmland is only 3.5% of the country, so almost nothing there can be farmed." What is the best correction using Card C?

    • The note is wrong because the farmland is 5%, the same as the valley and delta, so the whole valley is farmed
    • The note cannot be corrected, because Card C gives no figures for the desert
    • The note is right, because a share of 3.5% is too small to feed most of Egypt's people
    • The 3.5% is out of all Egypt, desert included; inside the valley and delta about 70% is cultivated

15. Use this

    Card F (made up for practice). Marlow's flood map in 2010 and in 2020. 2010: 40 homes; the flood zone is a strip along Mill Creek, and 6 homes lie inside it. 2020: 52 homes; the zone was redrawn wider after new measurements, and 11 homes lie inside the 2020 zone; 8 of the 52 homes lie inside the old 2010 strip. The 2020 zone includes the old 2010 strip. Key: shading = flood zone; small square = home. Note: a GIS overlay counts the homes where the layers overlap. Card G (made up for practice). Marlow's roads and services in 2020. Three roads: Mill Road, Oak Road and Ridge Road. Mill Road and Oak Road cross the 2020 flood zone at bridges; Ridge Road does not. The clinic stands on Ridge Road. Of the 11 homes inside the zone, 7 stand on Mill Road or Oak Road and 4 stand on a side street that joins Oak Road inside the zone. Key: shading = flood zone; line = road; cross = clinic.

16. 9.

    Ren writes: "Only 11 of 52 homes are at risk, so the clinic and roads are safe." What is the best correction using Cards F and G?

    • The note is right, since homes outside the zone are not shaded and so cannot be affected by a flood
    • Homes outside the zone can still lose road access, because Mill Road and Oak Road cross the zone at bridges
    • The note is right for the clinic, since it is on Ridge Road, and wrong for the three roads
    • The note is wrong because 11 of 52 is more than a fifth, which is too many for the roads to be safe

17. Use this

    Card F (made up for practice). Marlow's flood map in 2010 and in 2020. 2010: 40 homes; the flood zone is a strip along Mill Creek, and 6 homes lie inside it. 2020: 52 homes; the zone was redrawn wider after new measurements, and 11 homes lie inside the 2020 zone; 8 of the 52 homes lie inside the old 2010 strip. The 2020 zone includes the old 2010 strip. Key: shading = flood zone; small square = home. Note: a GIS overlay counts the homes where the layers overlap. Card H (made up for practice). Two readings of Card F. Reading X: "The share of homes in the flood zone rose because people kept building in risky places." Reading Y: "The share rose because the zone was redrawn wider."

18. 10.

    Esme writes: "Reading X is false, because the old-strip share barely moved." What is the best correction using Cards F and H?

    • Reading X is weak, not false: new building raised the old-strip share from 15.0% to 15.4%, a small effect
    • Reading X is the main cause, because the old-strip share rose and the new homes were built in the zone
    • Reading X cannot be tested, because the card does not give the builders' reasons
    • The note is right, since a rise of 0.4 points is within rounding and so no effect