The backwash effect (also known as the washback effect) is the influence that a test has on the way students are taught (e.g. the teaching mirrors the test because teachers want their students to pass).

The washback effect is the outcome of a test or an examination which results either in positive or in a negative way. There are two basic terms of the washback effect, which are the Positive and the Negative washback effect. Positive washback occurs when there is harmony between the teaching and the students' examination or a class test performance. The Negative washback effect occurs when there is no sync between what is taught and what is performed (such as narrowing down the content). Both of these types of washback influence the teaching as well as the learning process.