An inference is an educated guess as to why something is the way it is. In most cases, this inference stems from a previous observation. These observations and inferences are made every day whether we are aware of it or not. Today I observed that my friend walking out of an exam had a distressed look on her face. From that observation, I inferred that the test was difficult. I did not know for a fact that the exam was difficult, however, I understood from prior knowledge that facial expressions can indicate how a person feels about an exam. In this case, my inference was correct; I confirmed my inference by asking how my friend felt about the exam. Overall, the observation that my friend was distressed and my knowledge that she had just finished an exam led me to infer that the exam was difficult.
Comments
Be careful in what is an inference
I think you should be more particular about what is an inference and what is an observation. For example, a facial expression can be observed, but any attributable emotion to that corresponding facial expression is a inference. We use past experience to judge emotion from facial expression, but the expression itself is the observation and could have nothing to do with the current emotion being felt.
The sentence "Today I
The sentence "Today I observed that my friend walking out of an exam had a distressed look on her face" is poorly connected to the sentence prior to it. This almost seems as if it should be a completely new paragraph. At the very least this sentence can start with "For example" or somehow structure the paragraph in such a way to make it clear that you are transitioning from general information to a personal example to further explain the concept.