Always assessing students this way is not objective. Some students who do not take pencil and paper tests well may be bright, but teachers need to find creative ways to assess their students. Assessing students' products and performance clearly shows what the students have really learned. Assessment should cover higher level thinking skills, through essays or projects. Along those lines, process not just content needs to be assessed.
Students benefit when the teacher provides a rubric.
Individual Education Programs are set up for students with disabilities. This is through an overall assessment, not just one test. The I.E.P. only covers children who qualify for special education. Teachers must observe the need and make sure the students receive the help they require. This covers all people with perceived disabilities.