diff --git a/pages/classroom/classroom.js b/pages/classroom/classroom.js
index 12d6276..e1db95e 100644
--- a/pages/classroom/classroom.js
+++ b/pages/classroom/classroom.js
@@ -67,7 +67,7 @@ Page({
   },
   send_message:function(event){
     let {message_text} = this.data;
-	if(message.trim()==""){return;}
+	if(message_text.trim()==""){return;}
     message = new Message({
       text: message_text,
       class: this.class,