{"id":7437868,"date":"2026-11-08T08:00:00","date_gmt":"2026-11-08T13:00:00","guid":{"rendered":"https:\/\/www.learningandthebrain.com\/blog\/?p=7437868"},"modified":"2026-10-16T10:26:33","modified_gmt":"2026-10-16T15:26:33","slug":"interleaving-who-benefits-most","status":"publish","type":"post","link":"https:\/\/www.learningandthebrain.com\/blog\/interleaving-who-benefits-most\/","title":{"rendered":"Interleaving: Who Benefits Most?"},"content":{"rendered":"\n<p>For over three decades, cognitive science researchers have championed <strong>desirable difficulties<\/strong>. When teachers make learning <em>the right kind of hard<\/em>&#8230;<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Students have to think harder in the short term, so they<\/li>\n\n\n\n<li>Learn more over the long term.<\/li>\n<\/ul>\n\n\n\n<p>For instance: many of this blog&#8217;s readers know that students learn more from <em>retrieval practice<\/em> than from <em>simple review<\/em>. Because students expend extra mental energy trying to retrieve correct answers, they ultimately consolidate those memories more richly.<\/p>\n\n\n\n<p>Another strategy also generates enthusiasm in Team Desirable Difficulty.<\/p>\n\n\n\n<p>Imagine that I teach four parts of speech in my English class: <\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Monday&#8217;s class: nouns<\/li>\n\n\n\n<li>Tuesday: adjectives<\/li>\n\n\n\n<li>Wednesday: verbs<\/li>\n\n\n\n<li>Thursday: adverbs<\/li>\n<\/ul>\n\n\n\n<p>What should my students&#8217; homework schedule be? Should they practice those parts of speech in traditional &#8220;blocks&#8221;:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Monday&#8217;s homework: nouns<\/li>\n\n\n\n<li>Tuesday: adjectives<\/li>\n\n\n\n<li>Wednesday: verbs<\/li>\n\n\n\n<li>Thursday: adverbs<\/li>\n<\/ul>\n\n\n\n<p>Or should they jumble the practice problems together?<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Monday&#8217;s homework: nouns only<\/li>\n\n\n\n<li>Tuesday: adjectives (and nouns)<\/li>\n\n\n\n<li>Wednesday: verbs (and adjectives and nouns)<\/li>\n\n\n\n<li>Thursday: adverbs (and verbs and adjectives and nouns)<\/li>\n<\/ul>\n\n\n\n<p>In theory, this &#8220;jumbling&#8221; strategy should be desirably difficult; it even has its own name &#8212; &#8220;<strong>interleaving<\/strong>.&#8221; We have a good research pool exploring interleaving, and the results look encouraging. (Not &#8220;slam dunk,&#8221; but encouraging.)<\/p>\n\n\n\n<p>Researchers, of course, want to know if interleaving helps most students in most classes. That is: does it help 2nd graders learning to read? 6th graders studying history? Dyslexic students in a college chemistry class? And so forth. One <a href=\"https:\/\/www.nature.com\/articles\/s41539-026-00450-6_reference.pdf\">just published study<\/a> asks an intriguing question: does interleaving benefit underrepresented minorities (URMs) in college math classes?<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Math and Biology<\/h2>\n\n\n\n<p>Professor Steve Bennoun taught two sections of &#8220;Calculus for Life Scientists&#8221; in 2023. Both classes took a midterm exam and a final. The difference between the two sections: <em>how the homework was structured<\/em>.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Section A had traditional &#8220;blocked&#8221; homework for the first half of the term, and &#8220;interleaved&#8221; homework for the second.<\/li>\n\n\n\n<li>Section B reversed that pattern: &#8220;interleaved&#8221; homework for the first half of the term, and &#8220;blocked&#8221; for the second.<\/li>\n<\/ul>\n\n\n\n<p>So, did <em>all <\/em>students benefit from interleaving? Did some subsets of students benefit more? Did interleaving help more on the midterm or the final?<\/p>\n\n\n\n<p>Before I answer those questions, let&#8217;s take a step back to understand the researchers&#8217; methodology a bit more precisely. Over the years, researchers have identified several predictors for success in college math class. <\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Unsurprisingly, students who took a lot of math classes in high school often do well in college math classes. In other words: students with less HS math preparation &#8212; on average &#8212; get lower grades in college math classes. <\/li>\n\n\n\n<li>So too, first-generation college students &#8212; on average &#8212; get lower math grades. <\/li>\n\n\n\n<li>Underrepresented minorities, students with lower HS GPAs: these and other groups get lower college math grades. <\/li>\n\n\n\n<li>(I&#8217;m going to stop typing &#8220;on average,&#8221; but please assume that all statements about groups report average results, not individuals.)<\/li>\n<\/ul>\n\n\n\n<p>So, this research team has many subgroups to analyze when they ask their questions. What did they find?<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Midterm and Final<\/h2>\n\n\n\n<p>On the midterm exam, <em>URM students benefitted from interleaved practice<\/em>. More precisely, URM students who did interleaved practice problems scored <strong>about a half a letter grade higher <\/strong>than URM students who did blocked practice. Statistically speaking, interleaved practice didn&#8217;t help or hurt students in other groups.<\/p>\n\n\n\n<p>On the final exam, the news gets especially interesting. <\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" width=\"1024\" height=\"684\" src=\"https:\/\/www.learningandthebrain.com\/blog\/wp-content\/uploads\/2026\/11\/AdobeStock_506176022-1024x684.jpeg\" alt=\"\" class=\"wp-image-7447860\" srcset=\"https:\/\/www.learningandthebrain.com\/blog\/wp-content\/uploads\/2026\/11\/AdobeStock_506176022-1024x684.jpeg 1024w, https:\/\/www.learningandthebrain.com\/blog\/wp-content\/uploads\/2026\/11\/AdobeStock_506176022-300x200.jpeg 300w, https:\/\/www.learningandthebrain.com\/blog\/wp-content\/uploads\/2026\/11\/AdobeStock_506176022-768x513.jpeg 768w, https:\/\/www.learningandthebrain.com\/blog\/wp-content\/uploads\/2026\/11\/AdobeStock_506176022-1536x1025.jpeg 1536w, https:\/\/www.learningandthebrain.com\/blog\/wp-content\/uploads\/2026\/11\/AdobeStock_506176022-2048x1367.jpeg 2048w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<p>First, <em>students overall scored higher when they did interleaved practice<\/em>. The authors acknowledge that the difference wasn&#8217;t huge. From my perspective, that difference is impressive. Interleaving costs no money and takes the same amount of time. If students benefit from something that&#8217;s essentially free, let&#8217;s celebrate the win!<\/p>\n\n\n\n<p>Second, <em>students in several subgroups benefitted even more<\/em>.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>URM students<\/li>\n\n\n\n<li>First-generation college students<\/li>\n\n\n\n<li>Students who took fewer math courses in HS<\/li>\n\n\n\n<li>Even students who didn&#8217;t do so well on the midterm<\/li>\n<\/ul>\n\n\n\n<p>Interleaving gave students in each of those groups an extra learning boost. If a free study strategy helps everyone, and helps these students even more, we have good reason to sit up and take notice.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">The Whys Behind the Numbers<\/h2>\n\n\n\n<p>This research team, reasonably enough, wondered why interleaving helps students who (historically, on average) have struggled with college math. One potential answer sounds like this.<\/p>\n\n\n\n<p>Recall my grammar example above: nouns, verbs, etc. <\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Some of my students come to my class with lots of prior grammar knowledge. They know what an adverb is, and &#8212; crucially &#8212; they know <em>how to distinguish between an adverb and an adjective<\/em>. <\/li>\n\n\n\n<li>Other students, however, lack that prior knowledge. They&#8217;ve never studied modifiers, much less had practice distinguishing between them.<\/li>\n<\/ul>\n\n\n\n<p>Traditional &#8220;blocked&#8221; homework helps students study individual concepts. But it doesn&#8217;t let students practice deciding if a word is a noun or a verb. When midterms and finals ask students to make those distinctions, they suffer from this lack of practice.<\/p>\n\n\n\n<p>&#8220;Interleaved&#8221; practice solves this problem. Students get to practice both the individual concepts and the mental process of sorting one from another. That extra practice &#8212; that good kind of difficulty &#8212; increasing understanding, and hence test scores.<\/p>\n\n\n\n<p>This explanation, although fascinating, prompts a note of caution. The researchers found that some students benefited from interleaving even when they had appropriate background knowledge. In other words, it makes sense that students benefit from practice distinguishing between new ideas&#8230;but that isn&#8217;t the whole story.<\/p>\n\n\n\n<p>(While I&#8217;m offering methodology cautions, I should also note: students weren&#8217;t randomly assigned to these two sections, so the study&#8217;s findings are more &#8220;encouraging&#8221; than &#8220;decisive.&#8221;)<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">In Sum<\/h2>\n\n\n\n<p>We have many studies suggesting that interleaving can in fact be desirably difficult. This research &#8212; especially when replicated &#8212; gives us hope that it is especially desirable for students who have less preparation in math.<\/p>\n\n\n\n<p>We also have some potential insight into the reason that interleaving works. When students both practice skills <em>and practing distinguishing among skills<\/em>, they consolidate learning more effectively.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity is-style-wide\"\/>\n\n\n\n<p>Bennoun, S., Yan, V. X., &amp; Xu, A. (2026). Mixing problems increases performance of all students but especially of low-achieving ones in college calculus. <em>npj Science of Learning<\/em>.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>For over three decades, cognitive science researchers have championed desirable difficulties. When teachers make learning the right kind of hard&#8230; For instance: many of this blog&#8217;s readers know that students learn more from retrieval practice than from simple review. Because students expend extra mental energy trying to retrieve correct answers, they ultimately consolidate those memories [&hellip;]<\/p>\n","protected":false},"author":18,"featured_media":7447860,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[77,65],"class_list":["post-7437868","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-lb-blog","tag-interleaving","tag-math"],"_links":{"self":[{"href":"https:\/\/www.learningandthebrain.com\/blog\/wp-json\/wp\/v2\/posts\/7437868","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.learningandthebrain.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.learningandthebrain.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.learningandthebrain.com\/blog\/wp-json\/wp\/v2\/users\/18"}],"replies":[{"embeddable":true,"href":"https:\/\/www.learningandthebrain.com\/blog\/wp-json\/wp\/v2\/comments?post=7437868"}],"version-history":[{"count":9,"href":"https:\/\/www.learningandthebrain.com\/blog\/wp-json\/wp\/v2\/posts\/7437868\/revisions"}],"predecessor-version":[{"id":7448503,"href":"https:\/\/www.learningandthebrain.com\/blog\/wp-json\/wp\/v2\/posts\/7437868\/revisions\/7448503"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.learningandthebrain.com\/blog\/wp-json\/wp\/v2\/media\/7447860"}],"wp:attachment":[{"href":"https:\/\/www.learningandthebrain.com\/blog\/wp-json\/wp\/v2\/media?parent=7437868"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learningandthebrain.com\/blog\/wp-json\/wp\/v2\/categories?post=7437868"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learningandthebrain.com\/blog\/wp-json\/wp\/v2\/tags?post=7437868"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}