In the first grade lessons, students continue their study of shapes by learning to recognize parallel lines, parallelograms, trapezoids, half-circles, and quarter-circles. Defining attributes are distinguished from other attributes, and students draw shapes that possess given defining features. They compose both two- and three-dimensional shapes to form new shapes. They partition circles and rectangles into two and four equal shares and begin their introduction to the language of fractions by using the terms half, fourth, and quarter.
Students will learn the term polygon as it relates to all closed, flat shapes with three or more straight sides. Next, students identify the defining attributes of triangles. They reason about the defining attributes of triangles as well as non-defining attributes such as color, size, and orientation.
Students deepen their understanding that a square is a special kind of rectangle. They compare and contrast the defining attributes of squares and rectangles to uncover the similarities and differences.
Students identify the defining attributes of hexagons. They apply their understanding by sorting hexagons and non-hexagons, as well as creating and drawing hexagons of various sizes, orientations, and side lengths.
Students are formally introduced to parallel lines. They identify parallel lines in two-dimensional shapes using parallel lines testers. Students are then introduced to the defining attributes of trapezoids. They have the opportunity to reason about the defining attributes of trapezoids and non-defining attributes such as color, size, and orientation.
Students are introduced to the defining attributes of a parallelogram. They apply their understanding by distinguishing between parallelograms and non-parallelograms.
Students review the definition of a right angle and then identify right angles in two-dimensional shapes using the right angle tester. Students recognize that some shapes always have right angles, sometimes have right angles, and never have right angles.
Students are introduced to half-circles and quarter-circles using a foundational understanding of the defining attributes of circles. Students identify and sort half-circles, quarter-circles, and circles.
Students sort two-dimensional shapes based on their defining attributes.
Students combine two-dimensional shapes to compose new shapes. Students are challenged to create composite shapes from smaller shapes.
Students will work to decompose known shapes into their component parts. Students will explore and discuss the shapes and their attributes that compose, hexagons, pentagons, and other complex shapes.
Students engage in sorting activities to uncover similarities and differences of three-dimensional shapes. They use the terms faces, bases, and vertices to identify defining attributes.
Students combine three-dimensional shapes to compose new shapes. Students are challenged to create composite shapes from smaller shapes.
Students engage in partitioning circles into equal shares called halves and fourths (quarters). They create and identify circles correctly partitioned into equal shares and use the terms half, fourth, and quarter to name each share.
Students partition rectangles into equal shares called halves and fourths (quarters). They create and identify rectangles correctly partitioned into equal shares and use the terms half, fourth, and quarter to name each share.
The Grade 1 lessons address the fourth critical area of focus in the geometry domain of the Common Core State Standards (CCSS):
Students compose and decompose plane or solid figures (e.g., put two triangles together to make a quadrilateral) and build understanding of part-whole relationships as well as the properties of the original and composite shapes. As they combine shapes, they recognize them from different perspectives and orientations, describe their geometric attributes, and determine how they are alike and different, to develop the background for measurement and for initial understandings of properties such as congruence and symmetry (CCSS, 2010, p. 13).