Tests serve the purpose of judging the students' mastery of certain knowledge and skills, measuring growth over time, ranking students in terms of achievement, diagnosing student difficulty and determining the effectiveness of the curriculum. It depends on the instructional objectives and what has been stressed in class. An effective test should include only questions that address important outcomes of instruction. The use of the test results will determine the frequency of testing. Summative evaluation should be conducted less often.
More frequent evaluation is superior to less frequent.
Some item formats are less appropriate than others for measuring certain objectives. The length of a test will vary according to its purpose, the kinds of items used, the reliability desired, and the length of testing time available. Formative tests would be more in-depth and frequent than summative tests. The longer the test the more reliable it tends to be, but only so many items can be completed within a 50 minute class period. The difficulty of a test should depend upon its purpose.