Quizzes and regular tests can help to improve learning because it forces students to use their memories and mental fact retrieval methods to answer the questions. Students who engage in regular testing or quizzes are better able to recall facts and information than those who do not engage in regular testing.
Short quizzes and periodic tests benefit students because there is no pressure to cram or spend months studying, unlike state standardized tests. Students learn the material throughout the course of a school year and practice mentally retrieving facts, a practice that is beneficial for the future.
Short, low-stakes quizzes that won't break a grade help to cement information in a student's mind and allow for continued review without the need to cram information into the brain that will be quickly forgotten.