Summer School - Less Time! More Filling!
During the summer months we did a little homeschool every day, usually for about 1 hour total. I always made sure to include some math each summer; just tiny math workbooks, and a handful of problems each day. Once the kids were in high school, I found that SAT preparation books were the perfect summer review workbooks. Like the "Comprehensive Curriculum" workbooks for elementary school, but at a high school level!