Lots of options for three-year-olds Pre-K isn’t just for 4-year-olds in Arlington ISD. It’s for 3-year-olds, too! And we have several great options to fit your needs. Register your three-year-old today. Our fun-filled half-day pre-K for 3-year-olds is now at 21 elementary schools and its free for those who qualify. But if you don’t qualify,…