With so many boys in our house, I'm always on the lookout for hands-on learning activities. So I was thrilled to find a ton of very thorough, progressive K-3rd grade literacy centers from the Florida Center for Reading Research.
I also found so many free Montessori downloads for preschool, some of the best of which can be found here and here. There are even many for older kids here.
Plus, I was excited by all these math tubs/math centers (I confess, I am a homeschool junkie). These ideas are also helpful.