Increases in K-12 public school spending causally improve student outcomes — test scores, high school graduation, college-going, and long-run earnings — with the largest benefits for students in low-income districts; meta-analysis of all credibly-causal U.S. studies finds a $1,000-per-pupil increase sustained four years raises test scores ~0.03 SD and college-going ~2.8 percentage points, and court-ordered finance reforms have raised graduation rates in the poorest districts by roughly 7–12 percentage points.
Evidence: HighConsensus: Established Certified
early-childhood developmental risk / family income & poverty