In the year 1 C.E. the population of planet Earth was around 170 million. It is expected to reach 10 billion by the year 2100. You can explore the history of this world-wide population growth from 1 C.E. to 2050 on World Population : An Interactive Experience.
World Population : An Interactive Experience is a world map and timeline which visualizes global population trends over the last two thousand years. The map itself shows locations throughout history where more than 1 million people have lived. The map also includes a wealth of information about historical landmarks important to population trends. This information includes historical developments in science, food production, health, the environment and in human society.
The timeline running along the bottom of the map allows you to explore the data by year. Select a year from the timeline and you can see where the major centers of human population and the important historical developments of the selected year
As well as the interactive map the World Population History website includes teaching resources for six different lessons about world population growth. These lessons include teaching plans and student resources. Source