How to access iframe checkbox elements

Question

I have a web page that consists of a checkbox (parent) and on this same web page, I also have a iframe that is sourced from another page that displays a number of records, which

Answer 1

This works perfectly well

$("#select_checkbox").change(function(event){
    $("#content").contents().find(':checkbox').each(function(){
        jQuery(this).attr('checked', $("#select_checkbox").is(':checked'));
    });
});

where select_checkbox is the id of the parent checkbox, content is the id of the frame