Scientific models
a. are based on a set of observations
b. are used to replace experiments
c. allow the study of existing systems only
d. are rarely used

Scientific models are based on a set of observations. Scientific models are made using Scientific knowledge. Scientific knowledge is the use of proof and evidences when making decisions. The first step in problem solving is of course, identifying the problem. How could you solve the problem if there is no problem in the first place? When one gets to identify the problem, the next step is gathering of information to know more about the problem. One needs to get to know and examine the pros – the benefits – and con – the flaws – of the problem well. After doing all the needed data gathering and possibly, experimentation, when can start looking for the possible solutions of the problem.