As a K-12 homeschooled adult, the best curriculum I remember using was the ABEKA brand. It make it easy for my mom to teach us, and the fact that I remember 20-25+ years later means it genuinely had an impact on how I learned. Also, don’t be so worried about what “grade” they are in. Some kids need longer to learn certain subjects and others can advance through grades easier than others. When I was in 9th grade, my mom gave my older brother and I a 12th grade grammar book and said, “finish this with high marks and you won’t have to do more since it’s the top high school grade.” We got all A’s and didn’t do more grammar. I honestly loved that aspect and will do the same for my future children.