Dictate the part that is already made up, then ask Ss to fill out the blank with their own words.
T can provide an example by filling it out for weaker students.
Have one of the students write the part they dictated on the board. Ss can help the student, but the T will not give any feedback here. After the student is done, T comes up to the board and correct the sentence. Then T asks each student to read out their completed sentences. Interact with the students.