You can write a poem and a song by choosing your own style.

Can't! Judging from the requirements of the topic, it is indeed possible to write poems, but generally speaking, junior high school compositions only write narrative/argumentative essays, and rarely write expository essays. From the teacher's point of view, writing poetry is absolutely not supported and allowed. On the one hand, it is risky. On the other hand, you may not be able to write high-level works yourself without training, let alone the word limit.