Disable class language change after members > 0

app/templates/courses/classroom-settings-modal.jade

@@ -22,6 +22,7 @@ block modal-body-content
         - var aceConfig = view.classroom ? view.classroom.get('aceConfig') || {} : {};
         option(value="python", selected=aceConfig.language==='python') Learn Python
         option(value="javascript", selected=aceConfig.language==='javascript') Learn JavaScript
+      .language-locked Language cannot be changed once students join a class.
 
 block modal-footer-content
   if view.classroom

app/views/courses/ClassroomSettingsModal.coffee

@@ -16,6 +16,12 @@ module.exports = class AddLevelSystemModal extends ModalView
     else
       application.tracker?.trackEvent 'Create new class', category: 'Courses'
 
+  afterRender: ->
+    super()
+    disableLangSelect = @classroom?.get('members')?.length > 0
+    @$('#programming-language-select').prop('disabled', disableLangSelect)
+    @$('.language-locked').toggle(disableLangSelect)
+
   onClickSaveSettingsButton: ->
     name = $('.settings-name-input').val()
     unless @classroom