This has obvious advantages. First, it is taken seriously by students, and as a result it seems fair to make it a significant part of the students' grades, since they are going to typically put significant effort into preparation. Additionally, a well-written assessment can cater to students of various learning styles and effectively determine how they did in the preceding material. The disadvantages are also apparent. Many summative assessments are inadequate, and do not cater to students of various learning needs. Additionally, it can be too formal, and if it is relied upon too heavily then it can be used instead of formative assessments, which can completely leave some students behind.