The fourth purpose is to determine whether a KLA/topic outcome has been achieved. In an educational sense this is the main purpose of assessment, as the ultimate goal of education is to encourage and facilitate learning.
study skills noun Education (originally US) methods and techniques that aid effective learning, especially viewed as a set of skills that can be acquired or taught; the ability to study effectively.
Guessing meaning from context is an important skill for vocabulary you don't know in the IELTS test. Learn and practice here. Reading Lesson 7: Guessing meaning from context in the IELTS exam is an important technique that will improve your reading skills and the speed with which you can read. Obviously you do not have a dictionary in the exam so there are likely to be a lot of words from the reading text that you do not understand and you cannot check.