This document discusses different types of research designs, specifically experiments. It covers key components of experimental designs like independent and dependent variables, experimental and control groups, pre-testing and post-testing. Various threats to internal and external validity are explained, such as history, maturation, testing, instrumentation. Different experimental designs are presented like one-group pre-test post-test, static-group comparison. Strengths and weaknesses of experiments are that they allow manipulation and control but can lack generalizability and be expensive. Validity is important to evaluate whether conclusions can be supported.