I absolutely love CoreKnowledge and have been using it for multiple years for multiple grade levels now. It’s the one thing I 100% will not change for the upcoming school year. I would recommend a slow start to get used to it. When I started out, I only used Science and some History units. Eventually I switched over to the Language Arts units and since they cover so much history and science it actually saves me time on days when CKLA covers both, Language Arts and either History or science. This year I have used CKLA Grade 1 (currently finishing the last 2 units for the year) and CKLA Grade 4. We will be using CKLA Grade 2 and Grade 5 next year, as well as Science 2 and 5. For anybody interested I would say, start with the Language Arts units. My kids have learned so much!