Begin with a fragment, such as "green and bumpy." Ask your students to think of things that the fragment describes (such as a toad). Encourage your students to brainstorm descriptions of the object they have named. For example, you can ask them, "Where does a toad live?" and "What does it sound like?" Write the answers on the board.
Explain to your students that a complete sentence is about something. Show them how to build on the fragment by forming a complete sentence from the descriptions. For example, "The toad is green, sits on a lily pad and eats flies." Underline the key parts of the sentence, and ask the students questions about its meaning, such as "Where does the toad sit?" "Who sits on the lily pad?" and "What does the toad eat?"
Read some descriptive sentences from an age-appropriate text. Emphasize the importance of showing, not telling. Point out the sensory elements and ask your students to close their eyes and form a picture in their mind. Afterward, ask them questions about how they felt when they listened to the sentence. Write the sentence on the board and show your students how the author uses descriptive words to communicate images.
Have your students choose a descriptive sentence from a list you prepare. Ask them to draw a picture of what they "see" when they read the sentence, and then practice writing the sentence as a caption to the picture.