Draw points, lines, line segments, rays, angles (right, acute, obtuse), and perpendicular and parallel lines. Identify these in two-dimensional figures.
Classify two-dimensional figures based on the presence or absence of parallel or perpendicular lines, or the presence or absence of angles of a specified size. Recognize right triangles as a category, and identify right triangles.
Understand that attributes belonging to a category of two-dimensional figures also belong to all subcategories of that category. For example, all rectangles have four right angles and squares are rectangles, so all squares have four right angles.
Students will learn the distinction between lines, line segments, and rays. Then students will learn how to identify them in figures. After that, students will learn the distinction between parallel and perpendicular lines. Then students will learn how to identify them in figures. Students should also learn how to identify right triangles and non-right triangles. This topic is our first formal definition of parallel. Previously, parallel was understood informally to recognize trapezoids.