Explain the difference between an experiment and other types of scientific investigations. Help me

Question

anonymous · Answer

experimental investigation is designed in which variables are  manipulated, controlled, and measured in an effort to gather evidence. (All known variables have been identified!) must know this! and Has independent/manipulated and dependent/response variables.
comparative has no controls, a type of question, and might use variables. 
descriptive is when it is 'observed' and little is known. not an original hypothesis/research question. 
hope this helps