diff --git a/src/articles/ArticlePreview.js b/src/articles/ArticlePreview.js
index e07200939..271c4ca5c 100644
--- a/src/articles/ArticlePreview.js
+++ b/src/articles/ArticlePreview.js
@@ -39,6 +39,9 @@ export default function ArticlePreview({
   onUnhideArticle,
   isHiddenView = false,
   inSavedView = false,
+  // A student in several classes gets one merged classroom list, so each text
+  // says which class it belongs to.
+  showClassNames = false,
   // Someone is being shown this card rather than browsing it -- a teacher
   // previewing their class's feed. The card must look the same but do nothing
   // on the teacher's own account, so the personal controls come off.
@@ -289,6 +292,15 @@ export default function ArticlePreview({
   // tags; elsewhere publish time sits at the tail. `dontShowPublishingTime`
   // suppresses publish time only — the saved-time path is the replacement,
   // so it isn't gated on the same flag.
+  // Which class a text came from. Only for a student in more than one class:
+  // with a single class it is the same answer on every row, and the tab itself
+  // already says it. Computed here because both layouts below render a strip.
+  const classTags = showClassNames
+    ? (article.from_classes || []).map((each) => (
+        <MetaTag key={`class-${each.id}`}>{each.name}</MetaTag>
+      ))
+    : null;
+
   let savedTag = null;
   let publishedTimeSlot = null;
   if (inSavedView && article.personal_copy_saved_at) {
@@ -384,6 +396,7 @@ export default function ArticlePreview({
     // layouts so the meta/image markup isn't duplicated across the two.
     const metaStrip = (
       <MetaStrip>
+        {classTags}
         {article.topics_list &&
           article.topics_list.map(([topicTitle]) => <MetaTag key={topicTitle}>{topicTitle}</MetaTag>)}
         {article.matched_searches &&
@@ -625,6 +638,7 @@ export default function ArticlePreview({
           Saved · source · time. State badges (Simplified/Saved) get a subtle
           accent color; source/time stay muted. All on one row, small. */}
       <MetaStrip>
+        {classTags}
         {article.topics_list &&
           article.topics_list.map(([topicTitle]) => <MetaTag key={topicTitle}>{topicTitle}</MetaTag>)}
         {article.matched_searches &&
diff --git a/src/articles/ClassroomArticles.js b/src/articles/ClassroomArticles.js
index 0e8a374b4..2219f63f4 100644
--- a/src/articles/ClassroomArticles.js
+++ b/src/articles/ClassroomArticles.js
@@ -83,6 +83,16 @@ export default function ClassroomArticles() {
     );
   }
 
+  // The class tags need to know how many classes this student has, and that
+  // arrives on a separate request. Waiting is better than rendering the list
+  // untagged and having the tags pop in when getStudent lands -- the empty
+  // path above waits for the same reason.
+  if (student === null) {
+    return <LoadingAnimation delay={300} />;
+  }
+
+  const inMoreThanOneClass = student.cohorts.length > 1;
+
   return (
     <>
       <br />
diff --git a/src/teacher/myClassesPage/cohortsPage/ClassTexts.js b/src/teacher/myClassesPage/cohortsPage/ClassTexts.js
index 0647f19f4..37def7e96 100644
--- a/src/teacher/myClassesPage/cohortsPage/ClassTexts.js
+++ b/src/teacher/myClassesPage/cohortsPage/ClassTexts.js
@@ -44,6 +44,21 @@ export default function ClassTexts() {
 
   const { cohort, texts, student_count } = overview;
 
+  // A text in another language can be shared with this class, and then no
+  // student ever sees it: they only get the texts in the language they are
+  // learning. Seven classes are in this state today. The teacher is the one
+  // who can fix it, so the count goes to them rather than to the students.
+  //
+  // Only meaningful once the class has a language: without one there is
+  // nothing for a text to be "off", and treating null as a language would
+  // declare every text unreachable -- both alarming and untrue, since the
+  // student filter compares the article's language to the student's own and
+  // never consults the class's.
+  const offLanguage = (cohort.language ? overview.texts_by_language || [] : []).filter(
+    (each) => each.code !== cohort.language,
+  );
+  const offLanguageCount = offLanguage.reduce((total, each) => total + each.count, 0);
+
   const nothingShared = texts.length === 0;
   const emptyForEveryone = nothingShared && cohort.only_classroom_texts;
 
@@ -69,6 +84,21 @@ export default function ClassTexts() {
         </FullWidthErrorMsg>
       )}
 
+      {offLanguageCount > 0 && (
+        <FullWidthInfoMsg>
+          <span>
+            {offLanguageCount === 1 ? "One text here is" : `${offLanguageCount} texts here are`} not
+            in {languageName(cohort.language)} —{" "}
+            {offLanguage
+              .map((each) => `${each.count} in ${languageName(each.code)}`)
+              .join(", ")}
+            . Your students only ever see the texts in the language they are
+            learning, so nobody in this class can open{" "}
+            {offLanguageCount === 1 ? "it" : "them"}.
+          </span>
+        </FullWidthInfoMsg>
+      )}
+
       {nothingShared && !emptyForEveryone && (
         <FullWidthInfoMsg>No texts shared with this class yet.</FullWidthInfoMsg>
       )}
diff --git a/src/teacher/myClassesPage/cohortsPage/StudentsActivityOverview.js b/src/teacher/myClassesPage/cohortsPage/StudentsActivityOverview.js
index f81a9ba7a..a311578bd 100644
--- a/src/teacher/myClassesPage/cohortsPage/StudentsActivityOverview.js
+++ b/src/teacher/myClassesPage/cohortsPage/StudentsActivityOverview.js
@@ -32,7 +32,11 @@ export default function StudentsActivityOverview() {
   //Extracting the cohort data for the page title - for showing "no students" guidance and for deleting students from the cohort.
   useEffect(() => {
     api.getCohortsInfo((res) => {
-      const currentCohortArray = res.filter((cohort) => cohort.id === cohortID);
+      // cohortID comes from the route, so it is a string; the payload's id is
+      // a number. Compare as strings rather than relying on either shape.
+      const currentCohortArray = res.filter(
+        (cohort) => String(cohort.id) === String(cohortID),
+      );
       setCohort(currentCohortArray[0]);
     });
     //eslint-disable-next-line
diff --git a/src/teacher/myClassesPage/readingPage/StudentReadingInsights.js b/src/teacher/myClassesPage/readingPage/StudentReadingInsights.js
index 45a49d1aa..2c2152688 100644
--- a/src/teacher/myClassesPage/readingPage/StudentReadingInsights.js
+++ b/src/teacher/myClassesPage/readingPage/StudentReadingInsights.js
@@ -25,7 +25,10 @@ export default function StudentReadingInsights() {
 
   useEffect(() => {
     api.getCohortsInfo((cohortInfo) => {
-      let currentCohort = cohortInfo.find((each) => each.id === cohortID);
+      // Route params are strings; the payload's cohort id is a number.
+      let currentCohort = cohortInfo.find(
+        (each) => String(each.id) === String(cohortID),
+      );
       setCohortLang(currentCohort.language_name);
     });
     api.getStudentInfo(
diff --git a/test/teacher/textFilters.test.js b/test/teacher/textFilters.test.js
index 1ba39986a..afc9eb571 100644
--- a/test/teacher/textFilters.test.js
+++ b/test/teacher/textFilters.test.js
@@ -68,3 +68,19 @@ describe("sharedClassesOf", () => {
     expect(sharedClassesOf({ cohorts: ["nana"] })).toEqual([]);
   });
 });
+
+describe("cohort ids arriving from two endpoints", () => {
+  // /teacher_texts sends shared_with with numeric ids; the share dialog builds
+  // its objects from /cohorts_info. Those used to be stringified, so a text
+  // shared in this session and the same text after a reload produced two
+  // different chips for one class.
+  test("a class shared just now and the same class after a reload are one chip", () => {
+    const justShared = { id: 3, shared_with: [{ id: 7, name: "nana" }] };
+    const afterReload = { id: 4, shared_with: [{ id: 7, name: "nana" }] };
+
+    const filters = buildClassFilters([justShared, afterReload]);
+
+    expect(filters.filter((each) => each.name === "nana")).toHaveLength(1);
+    expect(filters.find((each) => each.name === "nana").count).toBe(2);
+  });
+});