We chose to supplement My Father’s World with ShillerMath because our daughter has a mechanic mind, yet does not comprehend what a circle, triangle, and such are. She’s able to count to a hundred easily, yet when I ask her to give me three things, she stares at the counters helplessly. I firmly believe in a Charlotte Mason approach for all other areas of the curriculum, as does the Hazells of My Father’s World. However, I’ve investigated many different math curriculum and I’ve found that ShillerMath is Montessori-based and his package includes everything I would need for the four years that it’s supposed to cover. It is a spiral mastery-based curriculum which is a huge plus for us. I worried with My Father’s World’s math lessons going by too quickly because it’s tied in with each lesson, but with ShillerMath, the children each can stay on a lesson until it finally clicks in their minds this is a circle, that is a square, etc. I am excited to round out my children’s education with this product and I will share how it goes for us, as much as I can.