German Christmas ... In a Nutshell?

My daughter's 4th grade teacher asked me if I'd like to give a "short" talk about Germany / German Christmas soon. Yes, yes - a thousand times YES!  :)  However, how to summarize all the wonderful things about Christmas time in Germany?

What should I discuss?

the lovely Christmas carols
Ihr Kinderlein Kommet 
O Du Fröhliche
or just the simple Stille Nacht

Of course, there is always food and all the wonderful cookies that might be placed on a Bunterteller (colorful plate) and given as a gift to family and friends. 
Vanillekipferl
Stollen
Lebkuchen
and so so many more ...

Christmas markets

and of course, the Christmas Tree
O Tannenbaum

Advent wreaths and
Advent calendars

What is your favorite part of a German Christmas?