How to Calculate the area of a circle given the radius

This video is about how-to calculate the area of a circle. It is in a very simple, and in an elementary school point of view. Of course, it can be done with either metric or imperial measures, as explained in the video. Only thing is that, it truly explains the simplicity of the calculation in every sense, which means, if you are not going for the ultimate knowledge on how things exist and survive in the form they are in, this video should be helpful. A grown man (woman) can't learn anything by watching this video, for it is much too simple, and on need-to-know basis, which I entirely disagree with.