Perimeter of 2D shapes. Keywords - perimeter, polygons, lengths in different units, formula, irregular shapes, equation, different triangles. Area as amount of space of a flat surface in 2D. Keywords - names, units, formula, 3D - objects, solids with curved surfaces, polygons, prisms, pyramids, volumes of solids, formula, units, capacity - concept, units, formula, measuring cups & volume vs capacity. Excellent for classroom teaching wit data projector & for use on a mobile.