Today’s Lesson is like the title of a book. It’s a headline.
It should, by itself, make sense to the student and the next teacher. It’s used in a variety of contexts, so it must be able to stand alone.
Here is a detailed and incredibly helpful guide to writing amazing headlines for the web. If you follow that advice, your "Today's lesson" will be excellent.
For example:
- Collocations for meetings
- Beginning your G.B.C. answer
- Pronouncing T endings
Why?
- It helps students review past lessons,
- it shows the teacher what the lesson was about, and
- it is the point of the lesson.