Continents, oceans, great rivers, mountains and deserts

Grade 6 Social Studies Worksheet - Challenge Me

Circle the best answer.

1. Read this first

   Use this

   Dry lands and map scale (cards A to D; areas are rounded). Card A, four deserts: Sahara (Africa, hot) | 9.2 million km2. Antarctica (polar, cold) | 14.2 million km2. Gobi (Asia, cold winters) | 1.3 million km2. Atacama (South America, along the Pacific coast) | 105,000 km2. A desert is a place that gets less than 250 mm of rain or snow in a year, whether it is hot or cold. Card B, yearly rainfall averages over many years: Manaus, Brazil, about 2,300 mm; Arica, Chile, in the Atacama, about 1 mm. Card C, causes: the Atacama is dry because cold water offshore cools the air and the Andes block moist air from the east. The Gobi lies far from the oceans and in the rain shadow of mountains such as the Himalayas. Antarctica's air is so cold that it holds little moisture, so little snow falls. Card D, a practice map (invented): the scale is 1 cm = 500 km. On the map, Town X and Town Y are 3.6 cm apart, and Mountain range M is 4.8 cm long.

2. 1.

   On card D, Town X and Town Y are 3.6 cm apart and 1 cm = 500 km. What is the real distance, Ari asks?

   • 500 km, the number of kilometers in one centimeter
   • 180 km, since 3.6 times 50 is 180
   • 1,800 km, since 3.6 times 500 km is 1,800 km
   • About 140 km, found by dividing 500 by 3.6
3. 2.

   Mountain range M is 4.8 cm long on card D. How long is it in real life, Bo asks?

   • 2,400 km, since 4.8 times 500 km is 2,400 km
   • 2,400 m, the same digits in a smaller unit
   • 500 km, the number of kilometers in one centimeter
   • About 104 km, found by dividing 500 by 4.8
4. 3.

   Two cities are 1,750 km apart. How far apart will they be on card D's map, Esme asks?

   • 500 cm, the number from the scale
   • 3.5 cm, since 1,750 divided by 500 is 3.5
   • 35 cm, since 1,750 divided by 50 is 35
   • 875,000 cm, found by multiplying 1,750 by 500
5. 4.

   Using card A, about how many times as large as the Gobi is the Sahara, Jun asks?

   • About 7.9 times, since 9.2 minus 1.3 is 7.9
   • About 70 times, since 92 divided by 1.3 is about 70
   • About 7 times, since 9.2 divided by 1.3 is about 7
   • About 11 times, comparing Antarctica's 14.2 with the Gobi's 1.3
6. 5.

   A student says, "A desert is always hot." How does card A answer, Kira asks?

   • Weak: a desert is defined by little precipitation, so cold Antarctica counts
   • Weak: card A is a table of areas, so it cannot say anything about heat
   • Weak: Antarctica gets more than 250 mm, so card A does not call it a desert
   • Strong: the Sahara is the largest hot desert, so heat is what makes a desert
7. 6.

   Using card C, which chain explains the Atacama's dryness, Luz asks?

   • Warm offshore water fills the air with moisture, and the Andes carry it to the coast
   • The Atacama is far from any ocean, so moist air cannot reach it
   • Cold offshore water and the Andes block moist air, so little rain reaches the coast
   • Sand soaks up the rain after it falls, which leaves the surface dry
8. 7.

   Why can a very cold place such as Antarctica be a desert, as card C suggests, Milo asks?

   • Deserts are defined by sand, and ice counts as a kind of sand
   • Very cold air holds little moisture, so little snow falls, even though ice stays
   • Antarctica is too far from the equator for rain or snow to fall anywhere, so it is a desert
   • Cold air holds a lot of moisture, but the ice stops snow from falling
9. 8.

   Manaus gets about 2,300 mm of rain and Arica about 1 mm. What helps explain Arica's tiny amount, Noah asks?

   • Arica lies where cold offshore water and the Andes cut off the rain
   • Arica is much hotter than Manaus, so its rain dries up before it falls
   • Manaus is the typical place and Arica is a mistake in the measurements
   • Rainfall depends on distance from the equator, and Arica is farther away
10. 9.

    Card B uses averages over many years. Why not use one year's rainfall, Tala asks?

    • Rainfall is the same in each year, so more years add nothing new to the answer
    • Averages are exact, so they fix the rainfall of each year
    • One year may be unusually wet or dry; many years show the typical amount
    • A single year is a later report, so it cannot be trusted
11. 10.

    Suppose another book gives the Sahara as 8.6 million km2, but card A says 9.2. Why might sources differ, Zee asks?

    • Older books measure in miles and newer ones in kilometers, so the digits differ
    • They may draw the desert's edge in different places or use newer measurements
    • One book must have a typing error, so it can be set aside without checking
    • The Sahara changes its area with each sandstorm, so any number is wrong