Are there a wide variety of formative and summative assessments?
The assessment guidebook, located in each eBook at Teacher -> Assessment (2nd tab at the top), discusses multiple forms of assessment that teachers can use. Each chapter in the Teacher Edition starts with an outline of suggested assessments for the chapter.
The frequent and varied assessment methods, coupled with observations of student work during class, give teachers the information they need to individualize their instruction and their assessments for the needs of their students.