This Google doc, compiled by a teacher, offers links to many articles related to the use of levelled books used with students.
Code-Switching and Symbolic Power in a Second-Grade Two-Way Classroom: A Teacher's Motivation System Gone Awry (research article)
In this article, Palmer notices that students code-switch (move easily between two languages within a conversation or utterance) despite the motivational system in place to discourage it. In fact, she states that the system offers students a tool for manipulating power in the classroom. The conclusion from this research is to encourage teachers to allow conversational code-switches while expecting students to produce spoken and written text in one language where appropriate. And, perhaps motivational systems for encouraging language speaking has unintended consequences. Found for thought...
The Canadian Modern Language Review publishes peer-reviewed articles on second language learning and teaching. It is a bilingual (French and English) journal of international repute, serving researchers and language teaching professionals interested in the learning and teaching of English and French as second languages (Canada’s two official languages), as well as the range of modern, indigenous, heritage, and community languages taught and learned across Canada. CMLR is available online and in print at Yukon Education..