Population Pyramid Power Nap

                Today in class we looked at population pyramids. We watched a video called TED ED that covered how population pyramids work and why we have them. A population period is sort of like a bar graph that has a vertical split and bar graph lines going to the left and right. Down the center of the graphs are five-year age groups that go from 0-4, 5-10, and so forth. The pyramid had men on the left and women on the right. Each five-year age group had a line going out in the appropriate direction, which could occasionally appear like a pyramid shape. This pyramid is an easy visual tool to help see where there is spurts of age throughout the groups, and can even be used to see where certain events took place, such as WWII where there was many deaths during the years the event was happening, making the lines shorter there. There are three main intervals for the pyramid. The three intervals are pre-reproductive, reproductive, and post-reproductive. Note that pre-industrial countries have higher life expectancy and lower child mortality, and vice versa. Also note that the picture of the man with his hands on his head is most likely losing his hair.