text: Agnes Martin's paintings are almost exclusively canvases of these objects scaled to 6' and filled with varying grids.
full_question: Agnes Martin's paintings are almost exclusively canvases of these objects scaled to 6' and filled with varying grids. In one work, a red one of these objects is stretched slightly to represent a peasant woman in two dimensions. Much of Ellsworth Kelly's work consists of random arrangements of these objects made from colored paper, such as in his Spectrum of Colors Arranged by Chance. While at Yale, one artist made hundreds of color-interaction studies by nesting these objects within each other; that series is Homage to [these] by Josef Albers. Holding these shapes to be the "first step of pure creation," Kazimir Malevich created a painting consisting entirely of a black one and showed a different one tilted slightly in White on White. For 10 points, name these four-sided regular polygons.
first_sentence: Agnes Martin's paintings are almost exclusively canvases of these objects scaled to 6' and filled with varying grids.
raw_answer: squares [prompt on "quadrilaterals"]