I use this activity for warming up or as a team competition game. It is very fast, it will not take you more than five minutes. I read aloud a line by line and students try to be fast completing the end of the sentence I have just read. You as a teacher can determine more definite rules like adding at least three words to each sentence or instead of shouting out the completed sentence students can write them. Adjust it as you wish. Add own phrases, delete ones you don't like.