One important thing is the growth of the students. They should be shown as having changed from when they first entered middle school. The relationships between students and teachers should also be included, as teachers often play a big role in middle school. Moreover, the sense of anticipation for high school or the next stage of life is essential. You can also mention the little details like what the students are wearing on that day, which can add more vividness to the story.
The emotions of the students, like excitement and sadness, are important. Also, the relationships such as friendships and crushes.
In a middle school graduation short story, it's crucial to include memories of the years in middle school. This could be academic achievements, like getting good grades or winning awards. And of course, the ceremony itself with all its elements like the principal's speech, the choir singing, and the hat - throwing at the end. Another important aspect is how the students are looking forward to the future while being nostalgic about the past.