This document discusses code-switching, which is the switching between two or more languages or language varieties in a single conversation. It provides definitions of code-switching and examples of code-switching between English and other languages. It then discusses reasons for code-switching, including filling a linguistic need, continuing the last language used, qualifying a message, specifying speaker involvement, conveying group identity, and excluding others from a conversation. Both advantages and disadvantages of code-switching are outlined, with advantages including improving class participation but disadvantages including potential confusion of students which can negatively impact lesson comprehension.