Check this 5 min. video clip to cardinal and ordinal numbers.
It does not, however, explain converting from a year (cardinal number) to a century (ordinal number.
Check this 2 1/2 min. video clip about deciding in what century is a year.
Check this 8 1/2 min. video clip about deciding in what century is a year.
After you finish taking notes and are working on your homework, if you need help, check this 6 min. video clip I created to help you create work with years (cardinal numbers) and centuries (ordinal numbers).