var whichUrl;
function openCDWindow(whichUrl) {
  var classroom = window.open("",'cdWin','status=0,scrollbars=1,menubar=0,resizable=1,toolbar=0,directories=0,location=0,width=690,height=530,left=20,top=20');
  if(classroom.location.href == document.location.href || classroom.location.href == "about:blank" || classroom.location.href == "/")
  {
    classroom.location.href = whichUrl;
  }
  classroom.focus();
  return;
}