You did a good job, Katrina and Kassia! ^_^ And there are also some tips you need to pay attention to:

练生词

农历是很古老(的历法)。 （“...是....“usually in the end of the sentence we use a noun o an adjective for making a conclusion, so that the person to whom you tell the information can easily understand it.）
我想我的生日是重要(的)。 (here you must put "的", because in Chinese almost all adjectives are in the form of "XX的")
这叫做一本书。 (sorry but this usage is so strange, in English maybe I can say "This is called a book." or "This is a book.", both seam right. But in Chinese the more natural form is "这是一本书。" Please pay attention here, the verb "是"(be) and “叫做/叫” (call) have some different meanings in different occasions. Usually, if you use "是", you'll be right all the time.)
中国农历的五月五日是端午节。 
我喜欢买古老(的)东西。
端午节是一个传统节日。
我喜欢学习中国历史。

练生词

农历是古老的。
我想我的生日是重要的。
这叫做一本书。
中国农历的五月五日是端午节。
我喜欢买古老的东西。
端午节是一个传统的节日。
我喜欢学习中国历史。