These focus on «how much» as in volume and as well as «how big, or small, or tall, or short, or other attributes of plane figures, as well as volume. (thoughtco.com)
Her topic was polygons, and she correctly explained that polygons are closed, plane figures with straight sides etc.. (teachermagazine.com.au)
Seven of Mangold's original woodcuts, Untitled A through G (2000) and Curved Plane Figure III (1995), are presented in dialogue with works by his contemporaries: Immovable Iconography (1990) by Nancy Graves (1939 — 1995) and Roses and Roofs (1987) by Janet Fish (1938 ---RRB-. (kemperart.org)