Chapter 1 KATAKANA
Katakana is primarily used to represent foreign words, except Chinese words, which, of course, are written in kanji. And this is exactly why we introduce katakana, first, instead of hiragana. Most of the words which are actually written in katakana are words which are more likely familiar to you, such as non-Japanese names, country names, various items, etc. Also, by expressing those familiar words in katakana, you should be able to know how different the Japanese pronunciation is, as compared with the original pronunciation.  

In learning katakana in this CD, you will not learn the characters in the order of the table provided below. You will learn about ten of them in each section so that you will become able to use them in reading and writing some meaningful words, mostly non-Japanese names and loanwords from English. The characters are carefully selected so that you will get used to relatively simple characters and become familiar with those which look alike. If you learn those look-alike characters at your early stage, you will have a better chance to differentiate them more easily. 

The table of katakana/hiragana is called the Gojuuon-hyoo, or the "table of 50 sounds", as it is made up of about 50 characters. The order in which these sounds are organized has a certain practical use, like alphabetical order in European languages. When a set of names or words are listed, like in telephone books, directories or dictionaries, etc., the order of the listing follows the order of the Gojuuon-hyoo.