Our Curriculum Choices for "Junior" Kindergarten

What we're using for our four-year-old next year...

My fourth child (nicknamed Peanut on the internet), is entering “junior” kindergarten next year. Junior kindergarten is the year before kindergarten, and while it’s not required by law to do anything official, nor is it advisable to be strictly doing “school,”, we do have a few play-based curriculum choices we’ll be using with her next year to familiarize her with numbers, letter sounds, and building her tolerance for sitting for five to ten minutes at a time doing “work.” She begs to do “school” alongside her older siblings, and this also gives her the illusion of schoolwork.