Call update_all on a relation, not 'update' which exists on a model

lib/tasks/one_off.rake

@@ -4,8 +4,8 @@ namespace :one_off do
     combined_school.update qualtrics_code: 5
     full_circle = School.find_by_name 'Full Circle High School'
     next_wave = School.find_by_name 'Next Wave Junior High School'
-    SurveyItemResponse.where(school: [full_circle, next_wave]).update! school: combined_school
-    full_circle.destroy
-    next_wave.destroy
+    SurveyItemResponse.where(school: [full_circle, next_wave]).update_all school_id: combined_school.id
+    full_circle.destroy!
+    next_wave.destroy!
   end
 end