Teachers must use a variety of both formal and informal assessments to gauge the extent of students' learning.  These assessments can serve both to evaluate the effectiveness of the teacher's instruction and to help the teacher plan for or modify future lessons and assessments. 

This is an example of a Content Area Reading Inventory that I gave to my students before I taught my first lesson.  They never received grades for the activity, as it is designed to help the teacher gauge the students' reading abilities.  Though this student performed reasonably well, I learned from this assessment that most of my students become frustrated with textbook-based activities when the answers are not in the text verbatim.