Students should be able to...
Picture sources:
Main pic: http://www.flickr.com/photos/jamescridland/613445810/
http://americanlivewire.com/overpopulation-how-sustainable-is-earth-as-the-population-rises/
http://www.bbc.co.uk/nature/humanplanetexplorer/life_events/birth
http://theapeonline.com/?p=4436
http://news.bbc.co.uk/2/hi/africa/6508055.stm
http://edition.cnn.com/2009/WORLD/asiapcf/01/22/china.migration.newyear/
Main pic: http://www.flickr.com/photos/jamescridland/613445810/
http://americanlivewire.com/overpopulation-how-sustainable-is-earth-as-the-population-rises/
http://www.bbc.co.uk/nature/humanplanetexplorer/life_events/birth
http://theapeonline.com/?p=4436
http://news.bbc.co.uk/2/hi/africa/6508055.stm
http://edition.cnn.com/2009/WORLD/asiapcf/01/22/china.migration.newyear/