The purpose of Grammar Effects is to be able to analyze and compose sentences.
Knowing Grammar Effects will help you to be an accurate reader. If you know Grammar Effects well enough to analyze a sentence into its parts, you can see whether you understand each part of the sentence. You can tell which parts are difficult to understand and which are easy. Then you can ask specific questions to get the help you need.
Knowing Grammar Effects will also help you to be a skillful writer. You can use the ideas from Grammar Effects to write sentences that have different lengths and use different patterns. Sentence variety will keep your reader's interest. Mastering Grammar Effects will make you able to express more of what you would like to say.