I love Horizons math for a whole host of reason. Horizons workbook pages are colorful and simple. They don’t require you to do lots of pages of busy work, but in the back of each Teacher’s Edition (TE) there are extra pages for the kids to use if you really do need some extra exercises to hammer home what they are learning. The answer sheets are easy to read and understand. It does get a bit tricky at the level of grade 4. The lessons back up and share a page with the next lesson, and not all the lessons are labeled nicely. Just remember to jot down at the top of such pages which lesson you are working on 😉
Another thing to keep in mind if you are buying Horizons via a used book site, the TE books have 2 parts! In the younger grades you don’t necessarily need the 1st book where the lesson plans are located, but you may want the second part where the answer keys are located. I learned this the hard way with my daughter’s Horizons Phonics this year.
I also love the fact that at the bottom of the TE lesson pages are bible verses to encourage and remind you why you are doing what you are doing. I love that!!