Kinaesthetic PowerPoint!
A somewhat pretentious title! The idea is that you create a map of your
classroom in PowerPoint, and then get students to move around in response
to changing scenarios. This exercise reinforces several basic population
concepts including distribution, density and migration push and pull factors.
Here
for example is my classroom: The students work out where they are!

A new slide shows the classroom with different environments overlaid. Students
must decide which environments to inhabit by moving around the classroom.
They must be able to explain their choices when questionned.

Time moves on and the presentation develops various scenarios, for example
a university town develops on the site of a coal mine, but the river becomes
prone to flooding events.

At
the end of the presentation most of the students should have migrated more
than once in response to various environmental or economic changes.
There is plenty of scope for discussion and development of "what if?" scenarios.
Download example PPT file
here. Obviously a new presenatation has to be developed for each classroom!