This article reports on the teaching of a unit of lessons which integrates mathematics with studies of society and the environment. The unit entitled "Population Growth Rates" was taught to a double class of Year 6 students by a team of three teachers. The objectives of the unit were: (1) to provide students with a real-world context in which to study the mathematical concepts and processes associated with large numbers and percents; (2) to increase students' awareness of the social effects of population growth rates; and (3) to provide students with an opportunity to explore real-world data, examine the features and trends in the data, and make reasonable conclusions. (Contains 8 figures.)