First of all, lets define each. Reliability refers to the consistency with which a test measures whatever its measuring. In other words, the extent to which an experiment, test, or measuring procedure yields the same results on repeated trials. Validity on the other hand, refers to how well a test measures what it is supposed to measure. However, there is a strong relationship between reliability and validity. To illustrate, for a test to be reliable, it has to be valid. Thats means validity is a precondition for reliability. As a teacher, I will make sure that the test constructs represents the content on which students are going to be tested. This is a simple way to assure the validity of my test. For example, in my writing class, the content will be the appropriate use of punctuation and the test then going to include items such as identifying question mark, comma, period, and so on.
As for reliability, I will retest my students after one week in the same content the appropriate use of punctuation and if the results are similar then my test is reliable.
I need this answer in another words.