Final answer:
The NAACP became involved in Reverend Oliver Brown's lawsuit as part of a broader strategy to challenge the separate but equal doctrine, ultimately leading to the landmark Supreme Court case Brown v. Board of Education, which ruled that segregated public schools are inherently unequal.
Step-by-step explanation:
The NAACP decided to challenge segregation in public education after a series of judicial victories against separate but equal graduate and professional schools. Thurgood Marshall and his legal team began addressing the separate but equal doctrine, specifically targeting public education. Encouraged by victories in cases like Sweatt v. Painter and McLaurin v. Oklahoma State Regents, the NAACP shifted its focus to elementary and secondary schools. The strategy included psychological studies by Kenneth and Mamie Clark showing the detrimental effects of segregation on Black children's self-esteem. The NAACP's involvement with Reverend Oliver Brown's lawsuit against the board of education in Kansas was chosen as a strategic fight against educational segregation, culminating in the Brown v. Board of Education case. This lawsuit challenged the Plessy v. Ferguson doctrine and the practice of segregating public schools.
In Brown v. Board of Education, the Supreme Court ruled unanimously that separate educational facilities are inherently unequal, thereby overturning Plessy v. Ferguson as it applied to public education. This decision paved the way for the desegregation of schools across America.