You need to prepare a lesson for that day of class, and set it in a context so that your principal can understand how it fits in.

你必须为观摩日准备教学内容，并让其融入统合的课程中。

youdao

This includes the teacher's ability to prepare a lesson plan focusing on the teaching aim and to work towards the aim with certain teaching strategies.

这包括师资的能力，编写教案侧重于教学目标，并努力实现的目标，具有一定的教学策略。

youdao

So Chile is a good lesson in how to properly prepare for quakes.

所以智利对地震良好的准备是一个很好的经验。

youdao

It's a lesson no one is prepared for, and ironically, you have no time to prepare.

CNN: Hockey player: What doesn't kill you ...