This learning sequence is designed to assist students to evaluate statistical reports to compare population numbers and life expectancy.

Students explore population clocks and learn that they are not real time counters of the population; rather they are mathematical models. The counter has been programmed to give a visual representation of the rate at which the population is changing. Our world population is increasing and the clocks are based on statistics rather than an actual count. They do not show the same figure at any instant because they are based on different assumptions about birth and death rates.

A range of tasks has been provided for each activity and you may wish to choose which ones are used according to student ability. Materials can be taken from each activity to construct worksheets for students to record their discussions, calculations and findings.

#### Activity 1: World population clocks

A number of internet websites display population clocks which give 'real time' estimates of the world's population. Links to some of these websites are provided and will be used for mathematical calculations.

On their website, United Nations Day: 24 October 2011, the United Nations Organisation deemed that the world's population had reached seven billion on 31 October 2011.

Refer students to the video of World population: 7 billion. It is important to note, however, that the various websites with population clocks are not synchronised and some organisations maintain the seven billionth inhabitant arrived at a later date.

#### Activity 2: Country-specific population clocks

Some students may need some assistance to calculate and substantiate the claim that the rate of Australia's population is increasing by one every 97 seconds as shown on the Australian Bureau of Census website population clock. The site provides details about the statistical assumptions to assist with this process.

World population clocks are based on birth and death rates. Country-specific population clocks require more data than world population clocks. A population clock for Australia considers birth and death rates as well as migration and immigration rates.

#### Activity 3: Life expectancy

The activities provide students with the opportunity to develop their spreadsheet skills. Some students may require some scaffolding activities prior to creating their own spreadsheets. As a starting point, students should complete the Life expectancy data table using information collected from People Facts: Life Expectancy.

When comparing countries, the life expectancy of its inhabitants can differ significantly. There is also a difference between male and female life expectancies in most countries and cultures.

Within a country's population, life expectancy can vary quite a lot between different ethnic groups. In Australia the most obvious difference in life expectancy is that between Indigenous Australians and the non-Indigenous population.

Students might choose to construct the table as a spreadsheet, using appropriate software. This will facilitate different sorting and graphing techniques.

#### Activity 4: Graphing data

Students will use the Life expectancy data table to create a graph. The table is a useful way to organise data, but graphs are useful in exposing patterns and differences in the data.