
Data sets available on the Internet are valuable resources for studying
real data to address questions that interest students. Teachers and
students can download data sets from the World Wide Web, collaborate in
online datacollection projects, and search electronic libraries and
data files. This example describes activities in which students can use
census data available on the Web to examine questions about population.
Working on such activities, students can also formulate their own
questions and use the mathematics they are studying to address these
questions. They can propose and justify conclusions that are based on
data and design further studies on the basis of conclusions or
predictions, as described in the Data Analysis and Probability Standard. 
Task
Examine the United States Census Bureau (www.census.gov) or the Statistics Canada (www.statcan.gc.ca) web site to identify the population of your home state or province. Examine the population data from the past fifty years. On the basis of the population changes reported over the past fifty years, would you predict that the population of your state or province will increase or decrease the next time a census is completed? By how much?
Using These Web Sites
This example includes links to the Web sites of Statistics Canada, and the United States Census Bureau. To go to these sites click on the desired link highlighted in blue letters or on the corresponding region of the map. Close the window of the Census Bureau or Statistics Canada Web site to return to the Principles and Standards site.
Finding Population Data in the United States Census Bureau Web Site
Since addresses for pages on the Web may change over time, we will provide general strategies for finding data for this activity. Once in the Census Bureau Web site, you may want to scan the page to find specific information or statistics for the category "people." Data for this task is likely to be found under "historical census data." If browsing the pages related to the category "people" does not take you quickly to the data you are looking for, you may also try doing a search by entering "historical census data" as keywords.
Finding Population Data in the Statistics Canada Web Site
Once in this site you may want to scan the page to find specific information for the category "Canadian statistics" and then "the people." If browsing the pages related to these categories does not take you quickly to the data you are looking for, you may also try doing a search by entering "population growth" as keywords.
Discussion
Teachers can use technology to enhance their students' learning opportunities by selecting or creating mathematical tasks that take advantage of what technology can do efficiently and well. Technology can provide access to real data on the World Wide Web that teachers can use to design tasks in which students address questions that interest them. Although the availability of real data on the Web opens up exciting learning opportunities, teachers should not assume that gaining access to the data is always straightforward. The role of the teacher is thus central to the success of this activity. Teachers need to select or design the tasks, decide when and how students will have access to the Web, what searching skills and strategies students will need, and how much guidance to give them. Students need to plan and make decisions about the data that should be retrieved and select and use appropriate statistical methods to analyze the data. Teachers and students need to consider possible ways in which the data can be represented and which software might help them organize, represent, and interpret the data.
Additional Tasks to Explore
 Where does your state or province rank in population nationally? Explain how you found this information. Develop a graph that shows the population of the United States (or Canada) by state (or province). You may want to use a spreadsheet to organize, sort, and then graph the data.
 The U.S. Census Bureau site includes a feature called "Projections" under the "People" heading. Determine which ten states are projected to be the most populous in 2025. Notice that the table of projected populations is in thousands. What does this mean? Make your own graph to show the projected populations for the ten most populous states in 2025.
 Statistics Canada contains a feature called Statistical Profile of Canadian Communities. Look at the information provided for your community (or one near where you live). What information is available? Choose a set of data about your community and make a poster to share this information with your class.
 Go to the U.S. Census Bureau's home page (www.census.gov). Note the current U.S. and world populations. Record both amounts. Wait and visit the home page again in one hour. How do the U.S. and world populations change? Visit the site the next day. How do the U.S. and world populations change? On the basis of this information, what could you predict for the populations of the United States and the world in one week? One month? One year?
 Locate a map on the U.S. Census Bureau site that displays the median age of the population of the United States by state. On the basis of this information, which states appear to be "young"? What do you mean by young? Which states are "older" according to the median ages? What can you say in general about the median age of the midwestern states?
 Investigate the distribution of the population of the United States or Canada by some attribute you choose (e.g., age or gender). Formulate questions to investigate, then search for and organize data to address these question.
Take Time to Reflect
 What kinds of questions are of interest to students and can be explored through data investigations?
 What mathematics content and processes can students learn through data investigations?
 How can data investigations help connect mathematics with other subjects the students are studying?