This isn't a comment on screen time, but some food for thought regarding letting the older kids play outside unsupervised. Did you know that stereotypical stranger abductions are actually vanishingly rare?

These stats are courtesy of Leonore Skenazy's blog, Free Range Kids:

Abductions in perspective:

Number of children age 2 – 14 killed in car accidents, as passengers: 1300
Number of children killed each year by their family members and acquaintances: About 1000
Number of children abducted in “stereotypical kidnappings” (kidnapped by a stranger for ransom or for sexual purposes and/or transported away) in 1999, the most recent year for which we have statistics: 115.
Number of children killed by their abductor: About 50.

It's actually more dangerous to take your kids in the car than it is to let them play in the backyard without supervision! :-)

We live in an apartment in the downtown core of a major city. What I wouldn't give to have a backyard where I could let my kids blow off steam while I work, cook or clean.