Primary Standard:
MAFS.4.G.1.1: Draw points, lines, line segments, rays, angles (right, acute, obtuse), and perpendicular and parallel lines. Identify these in two-dimensional figures.
MAFS.4.G.1.2: Classify two-dimensional figures based on 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.
MAFS.4.G.1.3: Recognize a line of symmetry for a two-dimensional figure as a line across the figure such that the figure can be folded along the line into matching parts. Identify line-symmetric figures and draw lines of symmetry.
Content Knowledge:
In the prior Unit students explored the basic concepts of angles. They will connect this knowledge and explore basic concepts of lines, to analyze and describe shapes. Students will begin by exploring lines and line segments as well as the special conditions these lines may occur in such as parallel, intersecting, and perpendicular. They will also be able to identify these lines in geometric shapes.
The ability to classify geometric shapes is dependent on students understanding of lines, angles, and the ability to measure angles. The classification of triangles, as well as other polygons such as quadrilaterals, are explored at depth in this level. The concept of line symmetry is introduced in 4th grade. Through investigations and discussions, students explore the meaning of symmetry, identify shapes with one or more lines of symmetry, and draw the line(s) of symmetry on shapes.
GCG 1 – Learning Goal: As a mathematician, I can Identify and draw polygons with given geometric attributes
- Step 1: Recognize and identify parallel and perpendicular lines and line segments
- Step 2: Recognize and identify geometric attributes of polygons, draw polygons with given attributes
GCG 2 – Learning Goal: As a mathematician, I can Use geometric attributes to classify triangles
- Step 1: Recognize side length attributes in triangles, use to classify triangles as equilateral, isosceles, or scalene
- Step 2: Recognize angle classifications within triangles, use to classify triangles as right, obtuse, or acute
- Step 3: Classify triangles using both side lengths and angles
GCG 3 – Learning Goal: As a mathematician, I can Use geometric attributes to classify quadrilaterals
- Step 1: Recognize and use the number of pairs of parallel sides to classify/sort quadrilaterals
- Step 2: Recognize and use the number of congruent sides to classify/sort quadrilaterals
- Step 3: Recognize and use the number of right angles to classify/sort quadrilaterals
GCG 4 – Learning Goal: As a mathematician, I can Identify and explain line symmetry in polygons