Simple Ajax Paging (See related posts)

<% if @lesson_pages.current.previous -%>
<%= link_to_remote 'Previous page',
:url => { :page => @lesson_pages.current.previous },
:update => 'my_div',
:loading => "Toggle.display('spinner');"
%>
<% end -%>

This assumes that your paging links are inside the DIV that is being replaced by the Ajax call.

I'll leave 'next' as an exercise for the reader.