Agile basically is very small waterfalls. Of course you need to think up front about what you need to do before you do it. The fallacy of the waterfall model is

Agile basically is very small waterfalls. Of course you need to think up front about what you need to do before you do it. The fallacy of the waterfall model is the idea that you can accurately predict the full structure of the system before you write the first line of code.