depending upon the browser…some are more forgiving than others.
the style related things that others are talking about will not make or break a page. (like the table versus <p> tags, head tag…whatever). at worst, something like ff might not render a box in a table with a decent amount of width if it is empty…but that won’t ‘break’ anthing.
however, depending upon how persnickity the instructors code viewer is you have a pretty glaring non-compliant HTML structure.
Line 9:
<ul type="circle>
syntactically fucked.