There’s no nice way to put this: Sex education in the United States sucks.

The Centers for Disease Control and Prevention (CDC) released new data today showing that fewer than half of high schools and only a fifth of middle schools teach all 16 sex education topics recommended by the agency. In a country where nearly half of teens report having had sex and nearly a quarter of new HIV infections occur among people under 25, that’s a dangerous level of ignorance to perpetuate.

Dr. Stephanie Zaza, director of the CDC’s Division of Adolescent and School Health, told The Daily Beast that, in comparison to findings from previous years, this year’s data shows a “mostly flat” trend, or “a lack of increase in the topics being taught in schools throughout the country.”

In other words, it’s not getting better.

The CDC’s findings are based on a 2014 survey that asked middle and high schools in 44 participating states what percent of schools cover essential topics ranging from the benefits of abstinence to STD prevention to condom use. These aren’t particularly radical topics; the CDC is hardly recommending that schools teach teens about sadomasochism or proper orgy etiquette.

Instead, the 16 topics are the most basic building blocks of safe and healthy sex: communication skills, avoidance of risky behavior, information about the transmission of HIV, and more. Which makes it all the more disappointing how unevenly U.S. schools cover them, if they do at all.

“We need to do a better job of giving our young people the skills and knowledge they need to protect their own health,” said Dr. Jonathan Mermin, director of the CDC’s National Center for HIV/AIDS, Viral Hepatitis, STD, and Tuberculosis Prevention, in a press release. “It’s important to teach students about healthy relationships and how to reduce sexual risk before they start to have sex.”

As it stands, students in the U.S. aren’t learning enough about prevention in advance. In the full range of figures from each participating state, a median of 72.6 percent of schools taught 6th- through 8th-graders about the benefits of abstinence and a median of 74.9 percent included information about HIV and STD transmission. But those figures were much lower for the importance of using condoms and instruction in condom use: 39.9 percent and 23.3 percent, respectively. Lower still was the median number of middle schools that taught all of the CDC’s recommended topics: 17.1 percent.

When asked why middle schoolers would benefit from being taught about topics like condom use, Dr. Zaza told The Daily Beast noted that schools have the ultimate authority in deciding what to cover and when, but added, “What we recommend is covering all of these topics prior to becoming sexually active. We know that about 30 percent of teenagers are already sexually experienced in the 9th grade, which would suggest that reaching them really has to happen in the middle school years.”

The CDC’s figures were higher and, more promising for grades 9 through 12, but the proportions were similar: Nearly 94 percent of schools taught high schoolers about abstinence and over 94 percent taught them about STD transmission but only 70 percent highlighted the importance of condom use and just 53.7 percent provided actual instruction in condom use. (Once again, all figures here are medians.) Only 45.5 percent of high schools taught all 16 topics.

The big picture here is that secondary schools are teaching kids about the dangers of unsafe sex but they’re not giving them all the tools they could use to avoid them. It would be akin to telling teenagers that bears are dangerous but placing more emphasis on staying indoors at all times than on camping safety. Some teens are going to go camping, some won’t. We might as well teach all of them to keep their food suspended in bags if and when they do.

One key difference in this analogy, however, is that STDs are millions of times more common than bear attacks. According to CDC data, almost half of the 20 million new STDs reported each year occur among people under age 24. That means that young people also account for about half of the $16 billion in health care costs that STDs cause each year.

Youth also account for a disproportionate number of new gonorrhea and chlamydia infections—diseases that, if left undiagnosed or untreated, can cause infertility among young women. Failing to educate youth about sex, then, can cause considerable long-term harm.

“Lack of effective sex education can have very real, very serious health consequences,” said Dr. Zaza. “Young people who have multiple sex partners, don’t use condoms, and use drugs or alcohol before sex are at higher risk for HIV and other sexually transmitted infections. School-based sex education is a critical opportunity to provide the skills and information they need to protect themselves.” The disparities in American sex education also vary widely by state, the CDC found. In Arizona, for instance, only 21 percent of high schools checked off all 16 items on the CDC’s list but New Jersey schools hit an impressive 89.5 percent. Arizona brought up the rear in the middle school rankings, too, making it the state where youth are most likely to learn the least about sex. In the majority of states, fewer than half of high schools and less than 20 percent of middle schools reached the CDC’s goal.

As The Daily Beast reported in September, some of this state-by-state variation can be attributed to differences in state laws on sex education. By a count of 32 to 22, more states allow parents to opt their children out of sex education than mandate sex education in the first place.

Only 18 states require sex education to include information on contraception and a mere 13 require their programs to be “medically accurate.” It is perhaps no surprise given this latest CDC report that Arizona mandates neither sex nor HIV education while New Jersey requires both.

Dr. Zaza told The Daily Beast that people who don’t receive accurate sex education information during youth may end up relying on their own, often “inaccurate” sources for protection. The consequences of being unprepared for sexual activity, she said, can include unintended pregnancy, HIV or STD infection, and a reduced ability to negotiate sexual situations or to seek out sexual health services.

“There are a number of things that we can think of as the harms of not providing this information,” she said.

The benefits of providing that information have already been proved. As the CDC notes, more comprehensive sex education is associated with youth waiting longer to start having sex, having fewer partners once they do, and using condoms more consistently. Less education and, well, let’s just say that over a quarter of a million babies were born to teenagers in 2013.

The CDC will collect this same data again in two years. Let’s hope that, by then, schools in the U.S. can manage to score higher than an F on sex ed.