As, as, as! and a paper tiger

I feel I'm still a low level English learner once in a while... no, no... very often. :)
To tell the truth, I'm often confused about the usage of articles(a, the, no-articles) and which I should choose, the singular form or the plural form. Besides the usage of the word "as" is very difficult for me because it has so many meanings and the part of speech often changes - such as adjective, adverb, and conjunction. However, I may as well tell myself that I don't have to care about those things. If the sun were to rise in the west, I wouldn't become a native English speaker. :)

Anyway, I'm extremely busy this month and next month because of so many festivals!

For instance:
The sports day(Field day, PE festival) in my daughter's kindergarten(preschool)
The sports day(Field day, PE festival) in my third son's elementary school(primary school)
The sports day(Field day, PE festival) in my eldest son's junior high school
The yagura festival in my city - a kind of harvest festival

They are killing me! But I'm a little bit lucky since my job doesn't wear me out as of now.

By the way, let me write down an interesting expression I found out on the Internet or somewhere recently.

A paper tiger:
According to my dictionary, it means that an enemy or opponent who seems powerful but actually is not. Sounds interesting! In Japan, we have the similar expression, which is "張子の虎(はりこのとら hariko no tora). hariko is sort of a doll made from paper. I also found out the similar one, which is "have no teeth". Apparently the meaning is the same as "a paper tiger".