The Grand Old Duke of York

The grand old duke of York
He had ten thousand men
He marched them up to the top of the hill
And he marched them down again
And when they were up they were up
And when they were down they were down
And when they were only half-way up
They were neither up nor down!
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Actions: Every time you sing the word "up", stand up. When you sing the word "down", sit down. On "half-way up", stand up with knees bent. Repeat the song a number of times, getting faster. Or, try reversing the actions (e.g. sit down on "up", stand up on "down"!)