Lesson 1.4: Water Footprints Theme: Citizenship

Transcription

1 Specific Objectives Students will understand that the magnitude of large numbers is seen in place value and in scientific notation. proportions are one way to compare numbers of varying magnitudes. different comparisons may be needed to accurately compare two or more quantities. Students will be able to express numbers in scientific notation. estimate ratios of large numbers. calculate ratios of large numbers. use multiple computations to compare quantities. compare and rank numbers including those of different magnitudes (millions, billions). Numerous scientists have conjectured about how long humans can sustain ourselves, as we cruise the solar system in our self-contained environment. One of the most important natural resources that humans need for survival is water. An influential United Nations report published in 2003 predicted that severe water shortages will affect 4 billion people by This report also said that 40 percent of the world s population did not have access to adequate sanitation facilities in Humans need clean water not just for drinking, but for necessary tasks such as sanitation, growing food, and producing goods. You will use a measure of water consumption called a water footprint that includes all of the ways that people use fresh water. According to Waterwiki.net, The water footprint of an individual, business, or nation is defined as the total volume of freshwater that is used to produce the goods and services consumed by the individual, business, or nation. 2 Goods are physical products such as food, clothes, books, or cars. Services are types of work done by other people. Examples of services are having your hair cut, having a mechanic fix your car, or having someone provide day care for your children. Fresh water is often used to make goods and to provide you with services. In this lesson, you are going to compare the populations of China, the United States, and India. You will go on to look at the water footprint for each nation as a whole and per person ( per capita ) to make some comparisons and to consider what this information might mean for the planet s sustainability that is, Earth s ability to continue to support human life. While there is no one definition of sustainability, most agree that sustainability is improving the quality of human life while living within the carrying capacity of supporting eco-systems. Carrying capacity refers to how many living plants, animals, and people Earth can support into the future. 1 Retrieved from Rajan, A. Forget carbon: you should be checking your water footprint. Monday, 21 April Link [ html] 2 Retrieved from

2 Problem Situation 1: Comparing Populations You will begin by thinking of various ways you can compare different countries populations. Scientific notation will be a useful tool because it is a way to write large numbers. Recall that a number in scientific notation is written in the form: M x 10 n where 1 M < 10; and n is an integer. (1) In 2014, the population of the United States was 317,000,000. Earth s population was about 7.2 billion. Write these numbers in scientific notation. (2) (a) Write a ratio comparing the U.S. population to the world s population using a fraction. How could you simplify the fraction so that it has smaller numbers in both the numerator and denominator? (b) The ratio in part (a) compared a part of the world s population to the whole world s population, so it is reasonable to re-write it as a percentage. Calculate the percentage Write a contextual sentence for this result, which is a sentence that follows the Writing Principle (That is: Use specific and complete information. Someone who reads what you wrote should understand what you are trying to say, even if they have not read the question or writing prompt.)

3 (3) In 2014, the population of China was 1.39 billion. Compare China s 2014 population to the world population with a ratio. Write your answer as a percent and as a fraction. Consider how many decimals to give in your final answer. (4) Compare China s population with the population of the United States using a ratio with the U.S. population as the reference value (denominator). Write a sentence that interprets this ratio in the given context (follow the Writing Principle).

4 Problem Situation 2: Comparing Water Footprints The population of the United States is the third largest in the world, exceeded only by China and India. Which country uses the most water? Which country uses the most water per person? We ll now explore this. The table below gives the population and water footprints of China, India, and the United States for Notice the units used, given in the column labels. Country Population 3 (in millions) Total Water Footprint 4 (in 10 9 cubic meters per year) China 1,346 1,368 India 1,241 1,144 United States (5) Re-write the information from the table above into the table below, expressing the numbers in standard notation and in scientific notation, rather than with the units used above. The cell for China s population is filled in already. Complete the other five cells. China Country Population 1,346,000, x 10 9 Total Water Footprint (in cubic meters per year) India United States

5 (6) (a) Complete this contextual sentence: The United States had about million people in (b) Write a contextual sentence describing the United States water footprint, using a number and word combination as in part (a). (7) Notice that the countries are listed in the table from highest to lowest population. Using the data on Total Water Footprint, rank the countries (from highest to lowest) according to their total water footprint. (8) In the fourth column in the table we want to put the amount of water used on average by each person in the country. This is the Water footprint per person (which is the same as water footprint per capita ) for each country. - Label this topic in the top row of column four, and write the units. - Calculate and write in the table the water footprint per person for each country. (9) Rank the countries in order of water footprint per person ( per capita ) from highest to lowest. (10) In 2011 the average person in the United States used how many times more water than the average person in China? Justify your response.

6 (11) Write a contextual sentence to explain the meaning of your answer to the previous question. (Remember the Writing Principle: Use specific and complete information. Someone who reads what you wrote should understand what you are trying to say, even if they have not read the question or writing prompt.) (12) In 2011 how many times larger was the population of China compared to the population of the U.S. Justify your response. (13) Write a few sentences relating the information of #11 and 12 and what this might mean in terms of sustainability.