fix

static/index.html

@@ -10,7 +10,7 @@
         <link rel="stylesheet" href="fractions.css">
         <script async src="https://arc.io/widget.min.js#i2pjQQrd"></script>
     </head>
-        <iframe src="/worksheets/index.html"></iframe>
+        <iframe src="worksheets/index.html"></iframe>
     </body>
     <script src="worksheets/api/lod.js"></script>
     <script src="worksheets/api/abcc.js"></script>