It’s the last period of a warm spring day at Hyde Park High School, but freshman in one classroom are sinking into down jackets, or have their sweatshirts pulled up over their heads. On the left side of the room sit mostly female students. On the right side, the teenage boys laugh quietly or make jokes.

Their postures aren’t surprising because this day, like every week for almost five months, it’s time to talk about sex.

Today’s lesson is about decision-making and consent.

What does consent mean, ask the instructors, Julia Goldstein and Rahul Kukreja, two 19-year-old pre-med students from the University of Chicago full of nervous energy. They’re both from the nonprofit Peer Health Exchange which contracts to brings in university students to teach high schoolers about sex education.

A student sitting near the front in a black head wrap and a bright blue puffy jacket raises her hand. It’s not just about someone saying yes, she says, but “it’s about genuinely wanting to do something with their own free will.”

That’s right, Goldstein and Kukreja both nod.

With a growing national movement against sexual harassment on campuses and in workplaces, and after the revelation of widespread abuse in Chicago Public Schools, more schools are teaching the meaning and practice of consent. Data from the U.S. Sexuality Information and Education Council show that teens in Illinois report higher rates of forced sexual encounters than the national average.

In the spring, legislators in Springfield passed a bill that mandates more comprehensive sex education. That includes writing into the state’s school code an explicit definition of consent. The bill is waiting for the governor’s signature.

“Teaching consent is critical in reducing both intended and unintended violence,” said Brittany Merritt, executive director and former Chicago program director at Peer Health Exchange. “It’s a critical skill for young people to develop more broadly. We teach affirmative consent and the onus is on both parties.”

While sex education is not mandatory in Illinois, any district that chooses to teach it has to include both consent, information about contraception and abstinence-based education. In Chicago, the district chose to mandate it for its schools. Health educators helped put together what advocates consider a mostly comprehensive sex-education curriculum.

But it doesn’t yet include consent — the district said they are in the process of adding that content.

Teachers may use the curriculum or schools may hire a non-profit like Peer Health Exchange to teach it or another series of lessons approved by the Office of Student Health and Wellness.

However, just how schools teach sex education can vary widely. Many parents in Chicago say their students were never taught sexual education, or that the lessons were spotty and inconsistent.

On consent education, Peer Health Exchange updates its curriculum as definitions of terms like consent change. For example, until several years ago people widely assumed that sexual activity was OK unless a partner said “no.” Now the group teaches affirmative consent.

“The onus is now on all the parties to express what they do and don’t want, and then listen to their partner” said Lisa Walker, who helped craft the curriculum taught by Peer Health Exchange volunteers. “That’s what it’s about rather than ‘it’s a yes unless they say no.’ “

It’s a lesson that sexual health educators hope students will take into all parts of life.

“This is how we set boundaries as children, how we prevent child abuse, how we help young people feel safe in their own bodies,” said Aisha Chaudhri, reproductive manager at EverThrive, a community health non-profit based in Chicago. Chaudhri helped the district write its curriculum as the education manager at the Illinois Caucus for Adolescent Health, and has reviewed outside sexual education curriculum taught in Chicago schools.

“It teaches them to ask what they need not just in sexual relationships but in life,” she said.

In the classroom at Hyde Park, both the peer educators and students take examples from real life as they discuss the topics of the day. “What kind of non-sexual things might someone try and coerce you to do?” Kukreja asks.

Drinking alcohol, suggests one girl. “Stealing a car,” suggests a male student, eliciting a small wave of giggling.

Goldstein doesn’t miss a beat. “Right. If [you] say anything other than yes, consent has not been given.”

For the student in the blue puffy jacket, the awkwardness of the Peer Health Exchange classes is still worth enduring to learn how to better navigate issues teenagers face.

“Some students might not have a lot of knowledge, and they may laugh, but it’s very informative,” she said.