This document discusses different types of knowledge: 1) Empirical knowledge is gained through the senses like sight, taste, touch, smell, and sometimes with instruments. Rational knowledge is based on logical truths. Intuitive knowledge is possessed without knowing where it came from. 2) Observations involve direct descriptions through senses, while interpretations build on concepts and experiences to further explain observations. 3) In experiments, scientists manipulate the independent variable and measure the dependent variable to search for cause-and-effect relationships in nature. Controlled variables are kept constant.