Answer:
youth.
Step-by-step explanation:
The school children in the passage symbolize youth.
The speaker observes the children playing during recess, which is a common activity for young students. The use of the word "Children" in capital letters suggests that the speaker is emphasizing their youthfulness and innocence. Additionally, the contrast between the school children and the later reference to the "Setting Sun" suggests a contrast between youth and the approach of old age or death. Therefore, the presence of the school children in the passage reinforces the theme of the passage as a celebration of youth and the beauty of the natural world.