A study published in the April issue of the American Educational Research Journal, for example, finds that kindergarten students learn more when they are exposed to challenging content such as advanced number concepts and even addition and subtraction. In turn, elementary school students who were taught more sophisticated math as kindergarteners made bigger gains in mathematics, reported the study’s lead author, Amy Claessens of the University of Chicago.

Another study, published last year by Dr. Claessens with co-authors Mimi Engel and Maida Finch, concluded that as things stand, many children in kindergarten are being taught information they already know. The “vast majority” of kindergarteners have already mastered counting numbers and recognizing shapes before they set foot in the classroom, Dr. Claessens and her co-authors noted, yet kindergarten teachers report spending much of their math teaching time on these skills.

The students don’t gain anything from going over familiar ground: In the article published this month, Dr. Claessens and her colleagues report that pupils do not benefit from basic content coverage, but that all the kindergarteners in the study, regardless of economic background or initial skill level, did benefit from exposure to more advanced content.

Discussions about how to improve learning for young children usually focus on the length of the whole school day or the number of students in classes, but rarely on what is taught during the hours school is in session. Increasing the time kindergarten teachers spend on more advanced math concepts may be a simpler and more cost-effective way to boost learning.

Annie Murphy Paul, in the New York Times, pointing out another reason why arguments against providing all children with comprehensive college-preparatory learning just don’t wash. Every child thrives when given challenging curricula.

The young mother’s voice shook with anxiety. She had just gotten her son’s third-grade test results from his school, and he had scored at the absolute bottom level in reading, and only a little bit higher in math.

“All year,” she said, “my son got mostly B’s on his homework and report cards. I monitored every one. And now I learn that all of that was a lie.”

Like many other low-income mothers of color in America’s urban centers, this Portland mother knew what low performance, especially in reading, meant for her son’s future. She’d even heard that Oregon’s prison planners used third-grade reading test data to determine how many new cells to add.

If she and her son’s school couldn’t find a way to turn those results around — and soon — she feared they amounted to a virtual death sentence.

I hear her words — and remember the fear in her eyes — every time I hear about yet another effort to eliminate the longstanding federal requirement that children in American public schools be tested once per year in grades three-eight and at least once in high school. Proponents of this change argue that students should be tested only once, each during elementary, middle, and high school, if that often.

I can only imagine how frightened that Portland mother would be if she didn’t have an objective check on what her son’s school told her at least by the following year — but, instead, had to wait all the way until he hit eighth grade. In the meantime, all she would have are the grades that research and experience tell us too often paint a too rosy picture of student performance.

Yes, I get that a lot of the anti-testing voices are from affluent parents. Certainly, when the results of state tests just reinforce the message (one they so often get) that their children are sailing along just fine, getting that reaffirmed next year doesn’t seem so important… But that so many policymakers don’t see through all this — and can’t imagine the anxiety of that mother and millions like her who can’t afford to wait five years for an honest evaluation of their children’s preparation for the future — is worrisome.

Education Trust President Kati Haycock, in the Huffington Post, offering a reminder of why testing is so important in helping all children get the high-quality education they deserve.