Adjective          Adverb

careful            carefully

happy             happily

Because these words are so much alike, it is sometimes hard to know whether you use the adjective or adverb form. Which would you say?

Anita worked very careful.

Anita worked very carefully.

In this example, carefully is right. It tells how Anita worked. It goes with, or modifies, worked, which is a verb. Carefully is the adverb.

Which of these two sentences would you use?

Snow Treasure is a real good book.

Snow Treasure is a really good book.

You want the word you choose to modify good, an adjective. Therefore, you need an adverb. Really is the adverb.

Remember:

Adjectives tell which one, how many, or what kind about nouns and pronouns.

Adverbs tell how, when, where, or to what extent about verbs, adjectives, and other adverbs.