Trees or Grass: Roots of Improved School Performance

Studies of 318 Chicago area schools found a positive association between school yard greenness and improved performance on math tests (and a less powerful performance on reading). Researchers dug deeper to determine whether the impact was related to all greenness or if it was associated specifically with either grass or trees. They found that only greenness from trees was associated with higher performance. 

Kuo, M., HEM, M., Sachdeva, S., Lee, K., & Westphal, L. (2018) Might School Performance Grow on Trees? Examining the link between “Greenness” and Academic Achievement in Urban High Poverty Schools. Frontiers in Psychology.