diff --git a/src/content/10/en/part10b.md b/src/content/10/en/part10b.md
index cff94915f7..e4815a056e 100644
--- a/src/content/10/en/part10b.md
+++ b/src/content/10/en/part10b.md
@@ -788,17 +788,21 @@ const BodyMassIndexForm = ({ onSubmit }) => {
         value={formik.values.mass}
         onChangeText={formik.handleChange('mass')}
       />
+      // highlight-start
       {formik.touched.mass && formik.errors.mass && (
         <Text style={{ color: 'red' }}>{formik.errors.mass}</Text>
       )}
+      // highlight-end
       <TextInput
         placeholder="Height (m)"
         value={formik.values.height}
         onChangeText={formik.handleChange('height')}
       />
+      // highlight-start
       {formik.touched.height && formik.errors.height && (
         <Text style={{ color: 'red' }}>{formik.errors.height}</Text>
       )}
+      // highlight-end
       <Pressable onPress={formik.handleSubmit}>
         <Text>Calculate</Text>
       </Pressable>