The central sentence of the third paragraph of the third grade "Kite" in the text is: "I am very happy after flying the kite." The central sentence of the kite lesson is: "I feel very happy after flying the kite." This sentence described the author's feelings and emotions when flying a kite. Through this sentence, the author expressed his love for kites and his yearning for free flight. It also showed the author's inner peace and joy.