MAFS.3.G.1.1: Understand that shapes in different categories (e.g., rhombuses, rectangles, and others) may share attributes (e.g., having four sides), and that the shared attributes can define a larger category (e.g., quadrilaterals). Recognize rhombuses, rectangles and squares as examples of quadrilaterals, and draw examples of quadrilaterals that do not belong to any of these subcategories.
In prior grades, students explored shapes, talking about the attributes that define each shape, such as number of sides and vertices. 3rd graders describe, analyze, and compare the properties of two-dimensional shapes, talking about the way’s shapes are alike and different.
In this Unit, students recognize that shapes can belong to groups. Rectangles, squares, trapezoids, and rhombuses are all quadrilaterals because they share the attribute of four straight sides (and four vertices). Now shapes have more than one name! A square is a square but also a quadrilateral, and a rectangle.
Through hands on experiences sorting and classifying shapes, constructing shapes, or drawing shapes that fit into various categories, students develop their visualization and special reasoning skills. This helps expand their geometric understanding.
Although 3rd graders are not required to understand angle measures, parallel or perpendicular lines, introducing students to look for right angles and parallel sides informally, understanding this basic terminology helps them describe shapes with more precision. It is not the goal of the standard to assess students on these terms.
GCG 1 – Learning Goal: As a mathematician, I will be able to use strategies to fluently multiply by 8
- Step 1: Connect x8 facts with x2 facts and x4 facts to build fluency
- Step 2: Decide when to apply the commutative property and other known facts for efficiency
GCG 2 – Learning Goal: As a mathematician, I will be able to identify & sort quadrilaterals based on their attributes
- Step 1: Sort shapes (polygons, non-polygons, and quadrilaterals) by their attributes
- Step 2: Identify & define quadrilaterals (rhombuses, rectangles, square, parallelogram, and trapezoid) using their attributes
- Step 3: Sort shapes using the attributes of quadrilaterals: number of sides, number of angles, whether the shapes has a right angle, whether the sides are the same length, & whether the sides are straight lines
GCG 3 – Learning Goal: As a mathematician, I will be able to compare & group shapes based on their attributes
- Step 1: Sort quadrilaterals by grouping them based on their shared attributes and explain these attributes can define a larger category
- Step 2: Draw examples and non-examples of shapes that do not belong to the categories: rhombus, rectangle, and square