Thaddeus Knows His Letters! Thaddeus Knows His Letters! Down Syndrome Add comments May 032016 your browser does not support the video tag. Leave a Reply Your Comment You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong> Name E-mail URI