Final answer:
Providing dictionaries for students to keep at their desks is not an effective way to encourage richer language use in the classroom.
Step-by-step explanation:
The correct answer is option 4) providing dictionaries for students to keep at their desks. While dictionaries can be useful tools for students to expand their vocabulary and learn new words, simply providing dictionaries does not actively encourage richer language use in the classroom. Encouraging students to use precise, descriptive words in routine moments, rephrasing student responses into more refined language, and using sophisticated language while discussing a book the class has just read are all effective ways to promote richer language use in the classroom.