Summative evaluation is the type used to evaluate an entire course after its completion. An example would be when you have students fill out an evaluation of your whole course at the end of the semester. An example of summative evaluation of student performance is the comprehensive final exam. This type of evaluation is useful to gather student's impressions of the course as a whole, or to evaluate student's general performance with the entire course's materials.
Formative evaluation is the type used to evaluate the course while it is in progress.
An example would be when you have students keep a journal of their course experiences. An example of formative evaluation of student performance are end of chapter exercises. Formative evaluation is useful to gather information regarding specific sections of your course, specific aspects that may change over time, or aspects you adjust in response to the feedback. We recommend you have a summative evaluation available as part of your course and encourage students to fill it out at the end of the course. We strongly recommend you poll students regularly throughout your course to see what they think of the course and the materials.