When the credits rolled after a screening of “Hidden Figures,” my fellow movie-goers applauded enthusiastically. I joined in the clapping for the black women scientists we’d seen portrayed on the big screen and for a movie that made us feel good.

I’m glad I also read Margot Lee Shetterly’s book on which the movie is based. Shetterly made me think.

A movie that exactly replicated a book would be unwatchably long, talky and confusing. Screenwriters need to make choices. They roll several characters into one who can represent the stories without cluttering the narrative. They add a bit of drama to transform events into emotionally resonant metaphor. They crank up the romance to keep us cheering.

The screenwriters who transformed “Hidden Figures” also made some choices that tell us a lot about how far we have yet to go in addressing the legacy of American racial oppression.

Katherine Johnson, Mary Jackson, Dorothy Vaughan and the other members of the segregated pool of mathematicians, known at the time as computers, worked at NASA’s Virginia research facility. They did have white peers who defied Jim Crow. No one ever took a hammer to a segregationist sign over a bathroom door as shown in the movie. But I concede that simply inviting a black colleague to a social event might have entailed a smashing of barriers in an individual’s own mind.

Segregation at the research facility faded away gradually by the late 1950s. In the 1940s, a black mathematician who does not appear in the movie, Miriam Mann, was in the habit of discarding a COLORED COMPUTERS sign when she found it on the table where she and her colleagues were expected to eat in the workplace cafeteria. Days or even a week would go by before an unseen hand replaced the sign. Mann would again stuff it in her purse and spirit it away for disposal.

“They are going to fire you over that sign,” her husband told her.

“Then they’re just going to have to do it,’’ replied Mann, described by Shetterly as tiny and unassuming.

Eventually, the sign stopped reappearing.

“The unseen hand had been forced to concede victory to its petite but relentless adversary,’’ Shetterly concludes.

Before the period in which the movie is set, a mathematician who is portrayed on screen was handpicked to integrate West Virginia’s state university. It was part of a multifaceted, measured campaign by the NAACP and others to dismantle what Shetterly aptly describes as “the system of apartheid that existed in American schools and workplaces.” The movie gives us only a glimpse of the black educators who were able to prepare Johnson to reach for the moon despite underfunded and under-resourced segregated facilities. We can only imagine the brilliance and talent that didn’t make it through.

When I was researching my book about race relations among young South Africans, an economist said to me:

“Just think where we could be if we had started in the 1950s investing in human development … if far more black people had come through the school system and entered university.”

Shetterly’s book raises the same question for America.

Johnson never gave that emotional speech about the segregated bathroom we see in the movie. She simply ignored the signs and was never confronted about using the “white” bathroom. She could have been. The illogical, uncertain nature of racial oppression meant you could never know when what was a mere mistake one day might be a fatal error on some other, or what whim would lead a white person to be accommodating one moment and the next bringing to bear the frightening power he or she wielded simply because of race.

It was Johnson’s colleague Jackson who was answered with laughter and bafflement when she asked a white colleague for directions to the bathroom in a part of the sprawling research campus that had no toilets designated for blacks. Shortly after that humiliating encounter Jackson ran into engineer Kazimierz Czarnecki. She vented. Czarnecki’s solution was to invite her to join his team. He put her at the controls of his wind tunnel from the start, tutored her in mechanics and co-authored her first report. He also urged her to continue her studies to make the leap from pool mathematician to engineer. As my husband asked, did the moviemakers think audiences would reject a film in which the only heroes were black women and an immigrant?

Jackson had to petition city officials, not a judge as depicted in the movie, to get permission to attend University of Virginia extension classes at Hampden High School in 1956. Two years after Brown v. Board of Education, Virginia was still resisting desegregation.

“Virginia, a state with one of the highest concentrations of scientific talent in the world (thanks to the space research center), led the nation in denying education to its youth,” Shetterly writes.

White segregationists in one Virginia county defunded their entire public school system rather than allow blacks and whites to study together. Those schools were closed for five years. White parents sent their kids to ostensibly private institutions to which segregationist politicians funneled tax dollars. Black parents sent their kids to live with relatives in places where they could go to school, but many in what became known as the “Lost Generation” fell permanently behind.

Jackson studied in the evening extension program with men who were her colleagues at the research center during the day. They weren’t quite as shocked when she showed up for class as they seem to have been in the movie. Instead it was Jackson who was shocked at the dilapidated condition of the high school reserved for whites.

“She had just assumed that if whites had worked so hard to deny her admission to the school, it must have been a wonderland. But this?” Shetterly writes. “Why not combine the resources to build a beautiful school for both black and white students? Throughout the South, municipalities maintained two parallel inefficient school systems which gave the short end of the stick to the poorest whites as well as blacks. The cruelty of racial prejudice was so often accompanied by absurdity, a tangle of arbitrary rules and distinctions that subverted the shared interests of people who had been taught to see themselves as irreconcilably different.”

Progress was made by people doing their jobs and bravely, quietly chipping away at injustice. The principled boss smashing segregation and the benevolent judge giving a bright black woman a fair hearing didn’t exist. The movie’s fictions may spare white feelings and protect white complacency, but they leave the mistaken impression that the goodwill of a few individuals is a solution to systematic human rights violations.

We live in a time when people seek out fake news to avoid inconvenient truths and indulge in snark instead of considered opinion. At the heart of “Hidden Figures," movie and book, is the lesson that facts save lives. Truth matters. See the movie. More importantly, read the book.