German is very hard language sometimes. But, you should know already that 'der' is masculine. Talking about male people/animals, der mann, der Professor, der lehrer. Die is Feminine. Female peoples/animals, Die Frau, die Professorin, die Kuh. Finally, Das is Nueter. Talking of human babies and animal babies, Das baby, das Kind, das Kalb... Do you understand a little better?
