What does "Think scientifically" mean? To answer that, first we have ask ourselves: "What is Science?" Science to the general public, are often seen as the combined name for three subjects: Biology, Chemistry, and Physics. It's not hard to see why, because these topics are taught in school as science classes. However, Science goes far beyond these three topics, and science is everywhere. According to Wikipedia, "Science (from Latin scientia, meaning "knowledge") is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe." If one read this definition carefully, one could note that not all knowledge can be scientific, and yet science provides the most valid and reliable knowledge one can obtain. If science is this "systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe." then science should apply in every aspect of our lives, and it does.(see picture) 
Science is the way to understand our universe based on evidence, tests, and rational reasoning. To think scientifically means to follow the scientific thinking principles such as: "Ruling out rival hypothesis", "Correlation vs. Causation", "Falsifiability", "Replicability", "Extraordinary Claims Require Extraordinary Evidence", and "Occam's Razor". Of course you all have heard of those, I assume. Unless you really hasn't study for this class at all. (HA! HA! Bless the curve! Wait there isn't a curve?!) Now how many of you have thought about applying those principle outside of when taking PSY101 tests? My guess is, not many of you do, certainly I don't, at least not all the time. Why should we think scientifically? We should because it separates us from ignorance. Next time when you hear a claim, you should ask for the evidence before you believe it. When you see an apple fell far from the tree, maybe you should pick the simplest explanation such as a person passed by and moved the apple, rather than believing an invisible being placed it there just to show you a sign that you should not follow your father's footstep. It also helps you to avoid making misjudgement about a race group based on the data of the percentage of criminals of that race compared to other race in a city, because there are a lot more variables go into it.(correlation vs. causation). In general, think scientifically makes you to reason rationally, it sets your mind free. Maybe you would find science much more interesting since the "known" in your old thinking became "unknown", so you feel the need to discover the unknown world, to obtain new knowledge. Once you became more knowledgeable, you gain the obligation to educate the ignorants(ignoramus? not sure which word to use :P ). And this is how humanity improve! Thank you for your time! Until next time! Good Night!
