Do students forget what they learned during summer vacation? In the United States, this is called the "summer slide." A study in 1996 found that students lost about one month of learning over the summer. Math skills dropped the most, but reading did not drop much.

However, newer research says that the way tests measure scores can change the results. Skills you do not use can still get rusty.

Many students find it hard to remember how to solve problems after summer vacation. In the United States, this is known as the "summer slide." A 1996 review found that test scores fell by about one month's worth of learning over the summer, especially in math and spelling, while reading dropped less.

Middle-class children even improved slightly in reading, but children from low-income families declined. A later study argued that much of the achievement gap between rich and poor students came from these summer differences. However, in 2019, researchers pointed out problems with how tests were scored and changed. After correcting for these problems, they found that most gaps already existed before children started school.

Researchers have been measuring the "summer slide," the learning students lose over summer vacation, for more than a century. In 1996, Cooper and colleagues reviewed 39 studies and meta-analyzed 13 recent ones. They concluded that test scores fell by roughly one month of grade-level learning over the summer, with the largest losses in math computation and spelling. Middle-class children gained slightly in reading, while low-income children lost ground.

Alexander and colleagues then followed children in Baltimore from first grade. In 2007 they argued that much of the income-based achievement gap at the start of high school could be traced to unequal summer learning. On this view, schools equalize opportunity, and summer is when gaps widen. In 2019, von Hippel and Hamrock showed how measurement artifacts can distort such conclusions.

Some test scales spread out differently as children age, and some studies switched test forms between spring and fall. Once these problems were dealt with, their most robust finding was that most achievement gaps already exist when children start school. Evidence that the gaps grow over summer was inconsistent. An analysis of about 3.4 million students found that summer losses are common, though not every student has them.