(CNN) To fully appreciate Bernice Sandler's seismic impact on equality for women in higher education, you have to go back to the dark ages of the early 1970s.

In those days, many universities had limits on the number of female professors they would hire. Salaries for female faculty members lagged behind those for men. Men's varsity sports received millions of dollars in funding while female athletes held bake sales to pay for their uniforms. Some women's teams had no locker rooms and had to dress in their dorms.

All that began to change in 1972 when Congress passed Title IX, the federal law that bars gender discrimination in education.

But the landmark legislation may not have happened -- at least not as soon as it did -- if not for the grassroots efforts of Sandler, who died January 5 of cancer at her home in Washington. She was 90.

Through exhaustive research, legal action and testimony before Congress, Sandler was instrumental in the passage of Title IX, which has helped level the playing field for millions of women -- especially athletes -- at colleges and universities across the country.

"My mother always said, 'I wanted to change the world, and I did.' She was a big believer in people having equal opportunity to do what they wanted to do," said daughter Deborah Jo Sandler, a family-law attorney in Northern California.

"She was stubborn and tough and just a true inspiration," Sandler said. "People would come up to her all the time and thank her."

For Bernice Sandler, then a part-time teacher and budding women's rights activist, it was a long, unlikely fight.

"I had no idea what I was getting into," she wrote in a bio on her website . "I had no legal, political or organizing experience and had no idea that the political and legal action I began would force open the issue of sex discrimination on campus."

A 'Eureka' moment

The catalyst for her activism came in 1969. Sandler had just earned a doctorate at the University of Maryland and although there were seven teaching openings in her department, she was not considered for any of them.

When she voiced her frustrations to a male faculty member, he told her she was perfectly qualified.

"But let's face it," he said. "You come on too strong for a woman."

Sandler, known to her friends as "Bunny," went home and cried. Then she began to read whatever she could get her hands on about sex discrimination.

During her research she came across a little-known executive order signed by President Lyndon B. Johnson that prohibited federal contractors from discriminating in employment on the basis of race, color, religion and national origin -- and it had just been amended to cover sex discrimination as well.

"It was a genuine 'Eureka' moment," Sandler later wrote . "I actually shrieked aloud for I immediately realized that many universities and colleges had federal contracts (and) were therefore subject to the sex discrimination provisions of the executive order."

Bernice Sandler speaking in 2010.

By then she had joined a small women's rights group, the Women's Equity Action League, which helped her file a class-action lawsuit against some 250 colleges and universities, alleging "an industrywide pattern" of discrimination against women in hiring.

Women in academia shared their stories with Sandler, who urged them to write their elected representatives. At the same time, Sandler began compiling data on hiring discrepancies and other inequities in higher education.

Later she testified at congressional hearings and helped Reps. Edith Green and Patsy Mink and Sen. Birch Bayh draft the legislation that would eventually become Title IX. In doing so she became the first woman ever appointed to a congressional committee staff to work on women's issues.

The final version of the bill, signed into law by President Richard Nixon, contained only 37 words:

"No person in the United States shall, on the basis of sex, be excluded from participation in, be denied the benefits of, or be subjected to discrimination under any education program or activity receiving Federal financial assistance."

The enduring impact of Title IX

At the time, few understood the historical significance of what Sandler had accomplished. Title IX's passage got little press.

But all educational institutions that receive federal funds, both public and private, soon realized they had to abide by its regulations.

Title IX applies to every aspect of education, including enrollment, courses, financial assistance, housing and student services. It has helped correct gender-based inequities in faculty hiring and pay while arming women to fight sexual harassment on campus.

Its impact has been most visibly felt in college sports, where resources for women have traditionally lagged far behind those for men. Boosted by better funding and facilities, women's participation in college basketball, volleyball, swimming and other sports exploded in the decades after Title IX.

Its effects also trickled down to high school sports. Before Title IX, one in 27 girls played sports, according to the Women's Sports Foundation . By 2016 that number was two in five.

"#TitleIX has opened the doors to colleges, universities, & locker rooms for our sisters, daughters, & friends. This wouldn't have been possible w/o Dr. Sandler's passionate devotion ..." US Sen. Patrick Leahy said on Twitter Tuesday.

In the 1990s the Supreme Court also ruled that Title IX requires schools to respond appropriately to reports of sexual harassment and sexual assault against students.

Buoyed by her work on Title IX, Sandler spent the latter half of her life fighting discrimination against women. She was appointed by Presidents Gerald Ford and Jimmy Carter to the National Advisory Council on Women's Educational Programs, where she wrote a report on how faculty members often unknowingly treat women and men differently in the classroom.

Later she became an expert on the issue of sexual harassment, conducting workshops, testifying in court and helping schools develop guidance and protocols. In 2013 she was inducted into the National Women's Hall of Fame

Activists and women across the nation are paying tribute this week on social media to Sandler's legacy.

"Thank you Bernice Sandler, 'Godmother of Title IX', for coming on 'too strong for a woman' and paving the way for the opportunities afforded so many girls and women today," said Cheryl Reeve, coach of the WNBA's Minnesota Lynx , on Twitter.

But some, including Sandler herself, have argued that Title IX has a long way to go before it eradicates decades of entrenched sexual discrimination.

"I was extraordinarily naive; I believed that if we passed Title IX it would only take a year or two for all the inequities based on sex to be eliminated," Sandler wrote in 1997. "After two years, I upped my estimate to five years, then to 10, then to 25, until I finally realized that we were trying to change very strong patterns of behavior and belief, and that changes would take more than my lifetime to accomplish."