This document discusses interaction analysis, which is a technique for systematically observing and categorizing classroom interactions. It describes Flanders' Interaction Analysis Categories System (FIACS), which codes teacher and student talk into 10 categories. FIACS can be used to analyze classroom dynamics, provide feedback to teachers, and study the effects of different teaching styles. However, it only focuses on verbal behaviors and can be time-consuming to code interactions. The document outlines how to conduct an interaction analysis using FIACS and what metrics can be calculated from the data.