It is critical to your students' success that you understand that whatever math series you are using does not provide review of the concepts you have already taught. It is unrealistic to assume that students will remember what you taught six or seven months ago when the high stakes testing begins.  Keeping that in mind, you need to provide review in all areas of your math curriculum every week. I know that time is the major reason teachers don't do this.  That is why setting up math centers that touch on each area of the math continuum is a must. These centers are to provide skill introduction and practice of critical concepts. They are not to be graded. You do not need more paperwork to grade.  Completion is important of course, but the most important reason you are providing these centers is to support your students' learning with concept introduction and concept practice.  These centers are NOT just for the kids that finish their work! It is far more important that your low kids spend time at these centers. They need introduction and additional practice time on concepts in order to internalize the learning.