Experimental Design in Psychology

Here are the links to the reading and can be used to cite the assignment: 

http://my.fit.edu/~gabrenya/IntroMethods/eBook/methods.pdf

https://scholarcommons.usf.edu/cgi/viewcontent.cgi?referer=&httpsredir=1&article=1002&context=oa_textbooks

Question:

The discipline of psychology often uses the classical experimental design as its research methodology.  First, based on your readings this week, explain the elements of the classical experimental design.  Is this design especially useful in dealing with causal relationships?  If yes, why?  If not, why not?

How useful is a classical experimental design in studying real world situations?  Please explain with an example.