diff --git a/frontend/src/platform/CourseView.jsx b/frontend/src/platform/CourseView.jsx
index 6530875..0783969 100644
--- a/frontend/src/platform/CourseView.jsx
+++ b/frontend/src/platform/CourseView.jsx
@@ -163,6 +163,7 @@ function ActivityRow({ activity, onOpen }) {
     <div style={{ borderTop: '1px solid var(--border)', padding: '0.6rem 0', display: 'flex', justifyContent: 'space-between', alignItems: 'center' }}>
       <button className={styles.linkBtn} onClick={onOpen} style={{ textAlign: 'left' }}>
         <span className={styles.stageCount}>{ACTIVITY_LABELS[activity.activity_type] || activity.activity_type}</span>{' — '}{activity.title}
+        {activity.is_required === false && <span className={styles.hint}> (optional)</span>}
       </button>
       {activity.complete ? <span className={`${styles.pill} ${styles.pillOk}`}>done</span> : activity.estimated_duration_minutes ? <span className={styles.hint}>~{activity.estimated_duration_minutes} min</span> : null}
     </div>
@@ -186,7 +187,8 @@ function ActivityDetail({ activity, onLaunchLab, onChange }) {
         {activity.complete && <span className={`${styles.pill} ${styles.pillOk}`}>complete</span>}
       </div>
       <p className={styles.stageCount}>{ACTIVITY_LABELS[activity.activity_type] || activity.activity_type}
-        {activity.estimated_duration_minutes && ` · ~${activity.estimated_duration_minutes} min`}</p>
+        {activity.estimated_duration_minutes && ` · ~${activity.estimated_duration_minutes} min`}
+        {activity.is_required === false && ' · optional'}</p>
 
       {activity.body ? (
         <div className="md" style={{ marginTop: '1rem' }}>