Objectives for this module include the ability to: (1) order objects by comparing a property which the objects have in common (such as length, area, volume or mass), (2) describe objects (length, area, volume, mass, etc.) by comparing them quantitatively using either arbitrary units of comparison or standard units of comparison, and (3) describe objects by making quantitative estimates of their dimensions. The general pattern of instruction is one of presenting the situation with as little instructor-direction as possible. After the participants have generated the data, then the sequence provides illustrations of how the instructor could guide the discussion toward a meaningful interpretation of the data gathered. The instructional component of the module consists of: Materials List, Pre-Appraisal, Instructional Activities, and Post-Appraisal. Also included are performance objectives, references, rationale, and duplicated materials. Because of the diagnostic data available in the pre-appraisal experience, it is possible to determine which instructional sequence appears to be most appropriate for which student. The time periods required for this instructional module are three hours of planning and 130 minutes of teaching. The population for which this instructional program has been found to be effective includes preservice and inservice elementary school teachers. (BR)