Educational psychologists investigate the impact of different types of instruction on learning. In one study, researchers taught a math lesson to 9th-graders using the "Inventing to Prepare for Learning (IPL)" instructional cycle. A second group of students received traditional "tell and practice" instruction. After the lessons, both groups studied a worked example of a math problem on their own. Then they took a test that included problems like the worked example. The journal Cognition and Instruction published the results in 2004. Pick the best description of this study: Group of answer choices an observational study to make an estimate or a claim about a population an observational study of an association between two variables. an experiment to establish a cause-and-effect relationship between two variables

Explanatory variable (independant variable / predictor variable) may explain or influence changes in a response variable.
Response variable (dependant variable) measures an outcome of a study.

Observational study observes individuals and records variables but doesn't attempt to influence the response (does not impose a treatment). It allows the researcher to directly observed the behavior of inteest rather than rely on the subject's self-descriptions (Survey) thus allowing the researcher to study the subject in its natural environment, thus removing the potentiallybased effect of the unnatural laboratory setting on the subject's performance.