There is growing interest recently in the outdoor environment surrounding schools where students spent time during breaks, in-school activities, and after-school programs. Several reviews have examined the impact of long-term exposures to nearby nature on students’ academic achievement, but none has focused on the effects of short-term contacts with nature on students’ cognitive performance. The aim of this review is to understand the context in which short-term passive exposures to greenness occur, how cognitive performance is measured, and the conditions under which cognitive benefits emerge at various educational levels. We reviewed 14 studies in the extant literature that report investigations involving students at different educational levels, from elementary school to university, in a short exposure to nature lasting from 10 to 90 min during a study day. The review shows that in 12 out of the 14 studies, across educational levels, cognitive benefits emerge in terms of directed attention restoration from mental fatigue due to contact with nature. A no-cost opportunity to sustain students’ cognition is a break in a green environment after mentally demanding activities.