Dear ShenLi,
Thank you for your suggestions of our curriculum! Actually, this is a language difference. 羊(yang in Pinyin and "young" as you mentioned in your last thread) refers to a general name of all these kinds of animals, including sheep and goat. If you try to search 羊 in google.com, you will find images of both sheep and goat.
With the concept of starting from simple and common words as much as possible in Chinese Curriculum, we give this one first. In Chinese Curriculum semester 2, you will find separate items for sheep and goat (start from Day 165). Sheep refers to 绵羊 and goat refers to 山羊. They are of higher level and provide more complex word combinations. You may find out that they all have “羊“ as their last words.
It is sometimes the same in English too. For example, you have "dog" which can be Bulldog, Poodle, Shih Tzu or Pug. In Chinese, we have "狗“ (or can be 犬) to refer to "dog", and we have different categories for dogs too, such as 斗牛犬, 贵宾犬,西施犬 or 哈巴狗 etc. It is just that there is no such a very simple and common general word for both sheep and goat as "dog" does in English. So in order to give a comprehensive idea of 羊 to the babies, we used pictures of both sheep and goat.
Welcome more opinions and suggestions!