Former history teacher Erich Martel, a proven expert on D.C. school mismanagement, suggested in my Nov. 24 column that some D.C. charter schools had more white students than he thought likely if admission by random lottery was the rule, as it is supposed to be.

I said I would check this out. All seven charters Martel identified as having above-average white percentages have answered my questions, as has My School DC, the city office that oversees the application and lottery process. As far as I can tell, they are all playing by the rules. But that doesn’t answer the question: Why do certain charters and regular public schools have more white and middle-class students than others?

Several middle-class parents, both white and black, gave me their view. They are adjusting to a system very different from what happened before charters arrived in the 1990s. D.C. has an extraordinary 45 percent of its public school students attending those independently-run public schools.

My School DC executive director Sujata Bhat said the only students admitted to charters other than through random lotteries are midyear arrivals and a few other exceptions. The Mathematica Policy Research group has been hired to study the process. Siblings get preference in the lotteries, and their numbers can be large. Karen Dresden, founder and head of the Capital City public charter school, said 50 of the 158 spaces in round one of her lottery this year went to siblings, seven of whom were white.

The charter school leaders all agreed that some charters — and regular schools — have unusual numbers of white students because they are located near areas with many white — and black — middle-class residents and have high standards that those parents seek. One college-educated black parent told me she had pulled her children out of one charter because its middle school did not meet her standards. Middle-class parents of every race are generally better equipped to research, do applications and provide transportation.

In the eyes of many parents, there is only one high-performing non-charter public middle school in the city: Alice Deal in Northwest. “The only way to get into it anymore is by living in Ward 3,” one parent said. She said those families most eager to apply to the charters that Martel listed are from east of Rock Creek Park and in the Georgetown/Glover Park area, near to Deal but outside its boundaries, “and then everyone else farther out from Deal.”

The charter schools Martel listed “aren’t full of white kids,” the parent said. “They’re full of kids who can’t get into Deal.”

Whites were not a majority in any of the schools identified by Martel. Martha Cutts, head of the Washington Latin charter middle and high schools, said: “We do not have ways of admitting more white and affluent students, nor do we make any special efforts to attract such students.” Just 33 percent of her students are white. The representative for the BASIS middle school said because of the lottery “we have no way of knowing” applicants’ race or economic status. Forty percent of BASIS students are white.

Officials at E.L. Haynes Elementary School (14 percent white), Two Rivers elementary and middle school (26 percent white), Yu Ying elementary school (27 percent) and Capital City Lower School (18 percent) said the same thing, Jessica Wodatch, executive director of Two Rivers, said one of her own teachers could not get her child admitted to her school because of the lottery.

The data show that, on average, schools with significant numbers of middle class students have higher achievement levels. But several D.C. charter schools with no or few middle class students do just as well. It might be best to study how they accomplish that, with well-trained and supported principals and teachers, since it is unlikely that there will ever be enough middle class kids to please everyone.