I used to teach a Yr4 class one morning a week, and they walked in dull as ditchwater.
So I ran this as they straggled in, and other music, (the music not the ivid) on the IWB - they were soon settled, jiggling and smiling and joining in enthusiastically and a tad more lively than they were
Supergrass - Coffee in the Pot.
http://www.youtube.com/watch?v=ivAblVqUBfo
It started their day with a song and a smile.
If they could get the 'Hey!' in the right place they were so pleased with themselves.