An antonym is a word that means the opposite of another word. For example "up" is an antonym of "down". Synonyms are words with the same or similar meaning. Synonyms for "Intelligent" are "smart" and "clever".
The resources above cover the following skills:
Vocabulary Acquisition and Use
Demonstrate understanding of figurative language, word relationships, and nuances in word meanings. [L.4.5]
Demonstrate understanding of words by relating them to their opposites (antonyms) and to words with similar but not identical meanings (synonyms). [L.4.5c]