3.3 To explain core concepts of testing

Validity: A test has to be valid, that is true. However, what makes a test valid? Validity in a test is how a test relates to the language course in real life, if it meets the requirements and if it really helps the teacher to understand students' knowledge and abilities. If a test is valid, is going to be related to the class, is going to be helpful and it is not going to be out of place. There are many types of validity, such the validity of content and the validity of criterion. The first one is related to the fact of analyzing if the content on a test is linked to what is going to be assessed and the latter is related to if the test really measures what is promising.

Reliability: If we can trust the results of a test, even under different environmental characteristics and different time and place, we can say that a test is reliable. Human beings are not able to produce the same results and scores in a test under this different characteristics, however, if the scores are closely the same, this test would be an almost perfect tool and the scores would represent the real proficiency of a student.

In a reliable test, errors in measurement are not expected and mistakes by the scorer are not even thinkable.

Practicality: A test should be helpful for a teacher, not detrimental. Under this idea, we can look in detail how sometimes a test can be a nightmare for a teacher if such test was not developed to be practical. By practical we mean easy to score, easy to modify, easy to apply and easy to understand. The items in a practical test should be objective, handy and must be easy to revise and grade.

Backwash: What we know as backwash in testing is the effect of a test in teaching and learning. For teachers, testing some skills may be a hard task and they test just the easiest skills, as reading and writing, mostly because there is a stronger evidence of learning under this methods. Unfortunately, this is the awful truth of many language centers, which do not test listening or speaking due to the hard work that this represents. However, backwash can be beneficial under certain circumstances, like paying more attention in the assessment of these skills which are known for being difficult to score.