This is a guest post from Leanne Powner, Visiting Assistant Professor in Government at Christopher Newport University. Leanne is also the author of the Empirical Research and Writing: A Political Science Student’s Practical Guide.
To begin my unit on global poverty and inequality in Introduction to International Relations, I asked students to pick a poor country from a list that I provided and use the World Bank World Development Indicators databank to extract information on population, GDP, and GDP per capita, as well as the composition of the national economy (percent from industry, services, and agriculture). We then constructed scale models of the size and composition of the economies out of three colors of crepe paper; they input their GDP and composition data into a Google spreadsheet which calculated the length of the streamers. Students attached the streamers to a sheet of paper showing the country name, GDP, GDP per capita, and population, and we taped them to the board. We compared these to ones I had made showing the US, Russia, and the Philippines (middle-income). This all seemed fine – the US’s was a bit excessive (see below) – until I explained that the scale on their models was 10 times greater than the scale of mine. 
Their 29 cm streamer would have been 2.9 cm using the scale for the US/etc ones. I drew this on one of the posters to demonstrate and showed them a model for Ethiopia (a low-income country) on the same scale as the US and Russia.
The difference in streamer lengths was staggering and really gave students a good idea of how relatively wealthy the US is. When presenting the streamers that I had made, I taped them to the bottom of the projector screen and presented them in the order of Philippines, Russia, US. The R
ussia one trailed on the floor, but after taping the US one to the screen, I retracted the screen up to the ceiling…. then rolled the ball of crepe paper all the way to the back of the classroom…. and then all the way back to the front again…. and there was still a pile of crepe paper left on the floor. Ethiopia’s, in contrast, was only about 6″ long. It was an absolutely priceless teaching moment for $3 in dollar-store crepe paper.
The basic spreadsheet, which includes a sheet that calculates streamer length from student data, can be found here. I am happy to share additional materials from this project on request to leanne.powner@gmail.com .