This document discusses sampling techniques used in education research. It defines population and sample, and describes several common sampling techniques: simple random sampling, systematic sampling, stratified sampling, cluster sampling, convenience sampling, purposive sampling, and snowball sampling. The advantages of sampling are that it reduces cost and time, resources needed, and increases data accuracy. Disadvantages include potential for bias, inadequate subject knowledge, difficulties selecting representative samples, sample variability over time, and some populations cannot be sampled.