When you can answer why, you have your purpose. The reason for doing something.
Sad to say that, that your purpose is a hand me down.
In order to pass the exams, and improve the test scores, in order to develop my own economic mind, in order to improve my ideology.In order to understand the knowledge in this field, to master the knowledge, so that I can become more knowledgeable and help others to solve their confusion in this are
To pass exam, so what? So what if you pass or not?
To improve test scores. So what? So what does it mean anyway? how do you know when a 78 a passing grade
is an improvement on 78 also a passing grade at a later test
Develop you economic mind, so what? How would you even know if it has "developed"?
A purpose allows you to know what you need to know, what you need to look for, what you need to learn and what you need to focus on.
I suggest stop trying to pretty it up with fancy words and get to the point. If you want to pass an exam so you can show you have knowledge needed to learn the next level for a career doing x. Then the point is I need to learn (name of sub-subject /section of the lesson plan so I can pass the grade for a career at X IS YOUR purpose.
Also stop trying to make do with just one purpose. In learning PhotoReading, the initial purpose might be to learn PhotoReading so that I can learn and study better. And you're first activation might be to get to know the steps of the system and ironically that's the first thing you're taught And with your focus on that purpose you are in step with your instructor (teacher / author) And that makes learning easier.
When the teacher says, today we are going to learn. There is your purpose, if your teacher says read chapter x of the book look at the title and decide what it's trying to teach you. When you do that have a focus and by having a focus you have your purpose, you have your why, the why are you doing that?