THERE’S BEEN a lot of snickering about the District’s plans to test its public school and public charter students on health and sex education. But the problems being targeted — rates of childhood obesity, sexually transmitted diseases and teen pregnancy among the highest in the nation — are deadly serious. Whether testing is an effective means for ensuring that young people are well informed remains to be seen, but the novel approach is worthy of a serious discussion.

The Office of the State Superintendent of Education (OSSE) is developing a 50-question exam to measure student knowledge of health issues ranging from nutrition and drug use to mental health and human sexuality. The test, which would be the first in the nation, would be administered in the spring on the District of Columbia Comprehensive Assessment System (DC CAS), although only schools — not individual students or teachers — would receive scores. Officials say the tests will provide a base line of student knowledge on these critical issues and a way to measure the job schools are doing in providing health education to students.

Widespread derision followed news of the testing. Could students major in sex? What about extra credit? And, more seriously: Is this really a top priority in a city where so many students lack basic reading and writing skills? We admit to having some of those doubts, but education officials are fairly persuasive when they talk about the terrible health conditions of children and young adults in this city.

Consider the high incidence of asthma and diabetes, obesity, HIV infection, drug addiction and teen pregnancy. Testing alone won’t result in better student understanding of these critical issues; curriculum and effective instruction need to be in place. But as Adam Tenner of MetroTeenAIDS said to The Post’s Bill Turque, “what gets measured gets done.”

Indeed, that seems to have been the D.C. Council’s intention when it passed the Healthy Schools Act of 2010. Sponsor Mary M. Cheh (D-Ward 3) professes otherwise, saying she had something less rigid in mind. But the legislation clearly orders OSSE to report annually on “student achievement with respect to health and physical education standards.” Debate about this program has been warped by the knee-jerk reaction people tend to have when sex and education are in the same sentence. Clearly school officials need to do a better job explaining the details of this program and dealing with parental concerns. But the program should not be dismissed out of hand.