1) The document discusses key concepts in research such as variables, hypotheses, models, and the scientific method. It explains different types of variables and their relationships.
2) Different types of reasoning used in research are covered, including deductive reasoning which moves from general statements to specific conclusions, and inductive reasoning which makes generalizations based on patterns in observations.
3) Sound reasoning is important in research to enhance results. Researchers employ curiosity to identify problems, propose hypotheses, test them, and draw conclusions in a self-correcting process.