This document provides an overview of different research designs used in second language research methods. It discusses what research design is, noting that it is a set of instructions for data collection and analysis. It then lists and briefly describes several common research designs, including experimental, survey, ethnographic, correlational, case study, and action research designs. The document goes on to discuss specific research designs in more detail, including survey research design, experimental research design, and case study design. It outlines the key components, assumptions, practical steps, and visual representations of these three research designs.