Fundamental modeling concepts are the basic building blocks of how something is designed or modeled. For example, when you build with Legos you have to make sure you follow instructions and put the blocks together in the right way to create something. You need to get the right colors, shapes, and sizes of blocks and put them together in a way that makes sense and looks good. In the same way, when a computer scientist designs something like a program or a game, they need to think about the fundamental modeling concepts like what data should be used, what algorithms should be used to process the data, and how the program should be structured. This helps the computer scientist make sure that their program is organized in the best way possible and works correctly.