Using two maps of the world, determine approximately how much of the surface of the earth is land and how much is covered by water. 

Materials

• Figs. 1.8.1 and 1.8.2
• Tables 1.1–1.6
• Globe
• Pencil or pen
• Colored pencils or crayons (optional)
• Calculator (optional)

Procedure

1. Compare the equal-area and cylindrical-projection maps (shown in Figs. 1.8.1 and 1.8.2) to a globe. Hypothesize which type of map you think is a better representation of the surface area of the ocean basins and continents. Write down your hypothesis, and make sure to include your reasoning.

2. Using Tables 1.1 and 1.2, mark and label the boundaries of ocean basins and continents on both maps (Figs. 1.8.1 and 1.8.2). For this activity, group the islands with the continent closest to them. You may use colored pencils or crayons to color-code the maps. Make a map legend that explains how the boundaries are labeled and how your coloring of the boundaries shows information.
    
3. Determine the surface area of the ocean basins and continents for each map by counting and recording the number of squares.
   
   1. If you are completing this activity in a group and splitting up tasks, make sure everyone is consistent in their methods. Be prepared to give reasons for your decisions. For instance, determine how the group will count squares that are partially land and partially ocean.
   2. Count the squares for the surface areas of each ocean basin and each continent on each map. Record this information in Tables 1.3 and 1.4.
       
4. Collect and record the square count for the surface areas of the continents and ocean basins from each group in the class. Calculate class averages. Record this information in Tables 1.3 and 1.4.
   
   1. Using the class average data, calculate the apparent area by multiplying the number of squares counted by the surface area of each square. 
   2. Record this data in Tables 1.3 and 1.4. Use the class average data for the rest of the procedure.
       
5. Rank the continents and ocean basins in order of size. Rank the largest as number 1, the next as number 2, etc. Record your data in Tables 1.3 and 1.4.
    
6. Fill in Table 1.3 and 1.4 with the accepted values for each continent and ocean basin given to you by your teacher.
    
   1. Rank the continents and ocean basins using the accepted value areas. 
   2. Record your data in Tables 1.3 and 1.4. 
7. Calculate the percentages of the surface area of the earth covered by the continents and by ocean water.
   
   1. Add up your calculated area for the continents and ocean basins in each map from Tables 1.3 and 1.4. Record this data under the columns “Total area equal-area” and “Total area cylindrical” in Table 1.5. 
   2. Add the surface area of continents and the ocean for each map to get the total surface area of earth. Record this number in Table 1.5.
   3. Calculate the percentages of the surface area of the earth covered by continents and by ocean water using the formula
      

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      Using the scientifically accepted surface areas for the continents and ocean in Table 1.5, calculate the scientifically accepted percentage of each.
       
8. Calculate the approximate volume of each ocean basin in Table 1.6. Use the values you calculated from Table 1.4, the given average depth of each ocean basin in Table 1.6, and the formula below to calculate the volume:
   

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   Volume = Area x Depth
   1. Rank the volume of the ocean basins by size for both both equal-area and cylindrical projection maps in Table 1.6.
   2. Rank the largest ocean basin as number 1, the next largest as number 2, etc.
       
9. Fill in Table 1.6 with the scientifically accepted values for each ocean basin volume (given to you by your teacher). Rank the largest ocean basin as number 1, the next largest as number 2, etc. Record your data in Table 1.6.