Each state has math learning standards that guide instruction and development of curricular materials from kindergarten through twelfth grade. These standards usually include a geometry strand. Some basic concepts that are common in primary texts can be viewed on-line in "Shapes, Shapes Everywhere," a geometry unit developed by the Mid-Continent Regional Education Laboratory (McREL).
By second grade, geometry lessons in math texts introduce students to components of shapes such as points, lines, line segments, rays, angles, polygons and circles. A polygon is a shape with at least three straight sides that connect at corners. Second graders are expected to explore ideas such as how to identify and compare quadrilaterals, which are four-sided polygons.
Some middle school math programs are based on a series of texts for each grade level, such as those in the Connected Math Project (CMP), with each text focusing on a single strand. An example is CMP's sixth grade geometry text, "Covering and Surrounding," which includes basic skills such as applying the formulas for area and perimeter to design problems.
In their book, "Math Matters," Suzanne H. Chapin and Art Johnson note the necessity of a strong foundation in basic geometry ideas in elementary and middle school. They imply that texts involving hands-on experiences, such as creating models, "move students to the higher levels of geometric understanding."