Researchers have long known about the “testing effect,” the phenomenon of improved performance through testing. William James, psychology professor at Harvard and author of The Principles of Psychology wrote in 1890,
A curious peculiarity of our memory is that things are impressed better by active than by passive repetition. I mean that in learning (by heart, for example), when we almost know the piece, it pays better to wait and recollect by an effort from within, than to look at the book again. If we recover the words in the former way, we shall probably know them the next time; if in the latter way, we shall very likely need the book once more.
In other words, students who want to memorize information should attempt to retrieve that information from their own memories, rather than review the material over and over from notes or a text.
This is, at their essence, what tests are intended to do. Tests ask students to look into their wells of knowledge, locate information, and express that knowledge on the page.
Not all tests, however, are created equal. Some tests are more effective in eliciting this positive effect than others. Many tests, including standardized tests, SATs and IQ tests, are designed to measure developed knowledge or abilities. They are “static,” and “summative,” in that they measure students’ sum total knowledge or ability at a fixed point in time. Summative tests do not allow for instructor input during the test and are not intended to shape future teaching. Therefore, no learning takes place during or as a result of the test. Complaints that excessive testing detracts from learning tend to be aimed at summative testing. As summative tests do not teach, and classroom hours spent engaged in summative assessments detract from hours a teacher has to educate her students, those complaints are probably well-founded.
“Formative assessments,” on the other hand, are designed to discover what students do and do not know in order to shape teaching during and after the test. Formative assessments are not meant to simply measure knowledge, but to expose gaps in knowledge at the time of the assessment so teachers may adjust future instruction accordingly. At the same time, students are alerted to these gaps, which allows them to shape their own efforts to learn the information they missed.
Roediger asserts that educators should be using formative assessments early and often in the classroom to strengthen learning during the unit rather than waiting until the end and giving a summative assessment. These repeated assessments curb the most ineffective type of learning, in which students wait until just before the test and then attempt to cram the material in over a short period of time. Research shows that cramming works in the short term, allowing students to regurgitate the information for an exam the next day, but it is a terrible strategy for ensuring long-term storage. Knowledge learned through cramming is less durable over time.