2. Purpose
The object is what it is about knowing, be it a physical object, a person, an animal or an idea, or anything else that can be learned.
There is an interesting relationship between the subject, who learns, and the object, what is learned, since, when these two interact, they have very different effects on each other. While in most cases the object remains unchanged, the subject, by knowing this first, changes his internal world, since he acquires new knowledge.
However, it should be noted that there are certain exceptions. An example of this would be in many scientific investigations in which the participants, who would be the object of study, change their behavior when feeling watched by the researchers, who would be the subjects (not in the experimental sense) that acquire new knowledge.
It is here where we enter the idea of objective knowledge and subjective knowledge, understanding this second as that knowledge acquired by the subject that differs from what the object of knowledge really is.
To understand it more clearly, regardless of what the object of knowledge is, the subject who tries to understand it may or may not grasp it in its entirety. The subjectivity of the subject is the abyss that exists between the knowledge that he has acquired and the real knowledge of the object. Really, reaching fully objective knowledge is very difficult.
Taking again the example of the biology class, the object as an element of knowledge would be the cell's own didactic unit and everything that is explained in it: parts, functions, cell types, cell reproduction ...
3. Cognitive operation
It is the act of knowing, a psychic processing that cannot be directly observed, necessary for the subject to know the object and have an impression of it.
It differs from thought in that cognitive operation is instantaneous, whereas thought, which would become the impression in the process of acquiring knowledge, lasts over time.
Although this operation is brief, the thought resulting from the action remains in the subject's knowledge for some time.
In the example of biology classes, cognitive operations would be the actions that students would take to assimilate the content, such as reading the textbook, listening and processing what the teacher explains.