Formal assessment is typically of two types: norm-referenced and criterion-referenced. Both types measure what a student has learned, use the same types of items, are judged by the same qualities of goodness (validity and reliability), and are useful in educational decision making.

• The norm-referenced assessment is broad in content, and it covers a wide range of grade-level material. Its purpose is to measure achievement in terms of how the individual compares to others who have taken the same test. Items reflect easier and harder material so that the complete range of possibilities of performance (both the low-functioning child and the high-functioning child) will be covered. The purpose is to compare an individual’s performance on a broad range of items with all others at the same age or grade range. A percentage ranking is a familiar way for reporting such scores.
• Criterion-referenced tests provide information on how an individual performed on a set objective or learning standard. The information gathered is much narrower in scope than a norm-referenced test. The result tells how the student is doing in learning an identified set of material. Emphasis is placed on what is learned, not on how that compares to others’ learning. Most teacher-developed tests fall into the category of criterion-referenced tests.