More population studying

Today in class we looked at various graphs for different countries, like Japan, Sweden, and an African nation who's name I forgot. The African nation had a high birth rate and most of their population was in the 15-30s. There was virtually no-one alive 70+. For Sweden, they had a lot of working class citizens 25-50 and a lot of old people. They had some young people, but not as much as the working class. And for Japan, they had a lot of old people, but no young people which do most of the jobs so they might be suffering economic issues. So I figured out today we have a test on Friday so I'm going to start studying but most likely I won't have to because I pay attention in class and Human Geo is one of my favorite classes so I usually pay attention and absorb any information or stories.