For the '17/'18 school year we are continuing our new math curriculum, EngageNY which is Common Core aligned, and available to us (on-line materials/pdf's, etc.) for no cost. (We will be making an annual investment in student workbooks, etc., but the cost is modest relative to purchasing a full "bells and whistles" program from one of the traditional curriculum development companies.  EngageNY has been adopted by the entire WSESU, grades K-6.

Parent support is available on this site, and there's a great parent/student "homework helper" workbook available at modest cost here.

For more info on math and the Common Core:

Parent Roadmaps to the Common Core Standards - Mathematics
These roadmaps from the Council of the Great City Schools provide guidance to parents about what their child will learn in mathematics and how they can help support their child's learning in grades K-8.

A Parent’s Guide to the Common Core Standards
A helpful article on that provides an explanation of the Common Core for parents.

From the VT Agency of Education

The Common Core State Standards (CCSS) were developed in collaboration with our education partners to establish clear goals for learning that will prepare children for college and the workforce. The standards represent an aspirational document, which is our best current description of what we want our students to learn and be able to do in English language arts (ELA) and mathematics.

The standards are not curricula. Local districts and teachers have authority over how to help students meet these standards. We help on the expertise and professional judgment of educators to figure out how to personalize instruction to achieve these goals. 
An impressive variety of instructional material for both math and science, including computer programming, and now, humanities for students of all levels.  Khan Academy has created a stunning number of online tutorials, and its immersive online environment is a focal point of our 8th grade algebra program.

Students ready for algebra work as a team three days/week on self-paced work via Khan Academy, and meet with Mary Beth Berberick, their middle school math teacher, for two of the five weekly advisory periods.  Students report very favorably on the experience, are making good progress, and have the chance to push themselves as far as they like.