Using interlocking cubes, square tiles, and linear pieces, participants will build two and three dimensional forms and will measure the perimeter and area of rectangles and the surface area and volume of rectangular prisms with manipulatives. Formulas for these calculations will emerge from the geometry of our constructions as patterns, then as generalizations, and finally as formulas. The units of inches, square inches, and cubic inches and their distinctions are clarified through these activities.