My district uses the math series My Math. We started using this series a few years ago and there are a lot of great things that I like. Mainly our team of six Kindergarten teachers like it because it allows us to follow the same structure (previously we didn't have a specific math series, but used a variety of resources to teach our math curriculum and standards). So, using My Math allows us all to follow the same plan and then add and supplement as we need for our individual classes.
My Math has some great online features as well. We are still adding and modifying it as we need in our classrooms. Right now, we are working on composing and decomposing numbers. My class makes these anchor charts to give the students a visual to refer to. We make one a day until we have them all completed. Then, they hang in our classroom and the students refer to them often. It is great when I see them using these anchor charts as an independent learning tool during work time.
