In my 7th grade algebra class we just watched the short video "World Population" put out by Population Connection (www.popconnect.org). My students loved it. This is the first time I've watched it with students. The video shows a world map of white dots each of which represent one million people. A clock ticks as the years go by starting from 1 A.D. all the way to projections in 2030 A.D. As the years advance you see the number of dots increasing to represent population growth. My students could not stop talking about how the population was growing, where it was growing, and when it was growing. They were clearly taken aback by the sudden explosion in population in the last decade. After watching the movie, they had no problem identifying that population growth most closely fits an exponential model. I highly recommend this video!