Final answer:
Beals and other African Americans' experience of entering Central High School was life-changing due to it being a direct challenge to segregation, evidenced by federal intervention and the hostile resistance they faced.
Step-by-step explanation:
The experience of crossing the threshold into Central High School in Little Rock, Arkansas, was a life-changing event for Melba Pattillo Beals and other African Americans because it represented a direct challenge to racial segregation and was a tangible application of the Supreme Court's Brown vs. the Board of Education decision.
One piece of evidence highlighting its significance is the federal intervention by President Eisenhower, who sent troops to protect and enforce the rights of the nine African American students to attend the school. This action underscored the importance of the integration struggle, not just in Little Rock, but nationwide.
Furthermore, the resistance faced by these students, including Elizabeth Eckford who was met with an angry mob, illustrated the harsh realities of racism and the potential danger of pushing against entrenched societal norms for racial equality. Despite such resistance, these actions gradually contributed to the unfolding civil rights movement that sought to dismantle segregation and push for equal opportunities.