Well I think this sums up children nicely! If I may be Mr Picky for a moment though?

"As they go outside to run, about and play."

The punctuation left me stumbling a little. I re-read it with the comma moved:

"As they go outside, to run about and play."

I also think you could capture their inherent humour by having:

"As they go outside, to run, laugh, and play."

Just my two pen'eth! It's still a lovely poem.