I studied all of the idioms today in Lesson 1 and Lesson 2.
--> I studied all of the idioms in Lesson 1 and Lesson 2 today.
Or:
--> Today I studied all of the idioms in Lesson 1 and Lesson 2.
Or:
--> Today I studied all of the idoms in Lessons 1 and 2
Just my two cents.