在英文写作中，描述有一节数学课可以遵循以下结构：

首先，介绍这节数学课是在哪个学校、哪个年级上进行的。比如：

I had a math class in my high school today.

接着，可以描述这节课的教学内容或者老师的讲解方式。比如：

Our teacher introduced us to a new concept in algebra today - quadratic equations.

然后，可以描述这节课的学习氛围，以及自己的感受。比如：

The class was very engaging and interactive. We worked on problems in groups and the teacher provided helpful feedback. I found the lesson challenging but rewarding.

最后，可以总结这节课的收获和学到的知识。比如：

Overall, I learned a lot from this math class and I feel more confident in my ability to solve quadratic equations. I'm looking forward to the next lesson!