Quadrilaterals: Types and Properties
Lessons in this chapter
About Quadrilaterals: Types and Properties
Geometry in 3rd grade narrows to one family, the four-sided shapes, and asks kids to classify by property rather than by appearance.
Understand the Properties of 2D Shapes sets up the vocabulary the classification needs: sides, angles, parallel lines, equal lengths. Without those terms a child can only say shapes look different, which is not a classification.
Identify Different Types of Quadrilaterals introduces the square, rectangle, rhombus, parallelogram and trapezoid. The idea that trips kids up is that the categories overlap. A square is also a rectangle, also a rhombus, also a parallelogram, because it satisfies all of their definitions at once.
Compare Types of Parallelograms sharpens that. A parallelogram needs two pairs of parallel sides. Add four equal sides and it is a rhombus. Add four right angles instead and it is a rectangle. Add both and it is a square. Seeing the family as conditions stacking up is far more useful than five separate pictures.
Understand the Properties of 2D Shapes, Identify Different Types of Quadrilaterals and Compare Types of Parallelograms are the chapter's three lessons, each a worksheet worked in the page and marked as your child answers. Sorting by property rather than by how a shape looks is the whole of it, which is why the practice keeps asking whether a square is also a rectangle. All three are free.
Frequently asked questions
The properties of 2D shapes in general, then the types of quadrilateral, then a closer comparison of the parallelograms: squares, rectangles and rhombuses. The point is to classify by sides and angles rather than by appearance. It sits in Geometry (3.G), which asks 3rd graders to recognize shared attributes across shape categories.
Any closed shape with four straight sides. Squares, rectangles, rhombuses, parallelograms and trapezoids are all quadrilaterals.
Yes. A rectangle needs four right angles, and a square has them. A square is also a rhombus and a parallelogram, because it meets all of those definitions too.
Two pairs of parallel sides. Add four equal sides and it becomes a rhombus; add four right angles and it becomes a rectangle; add both and it is a square.
Because each is defined by conditions, not by a picture. A shape belongs to every category whose conditions it satisfies, which is why one shape can have several names.
A quadrilateral with at least one pair of parallel sides. It is the loosest of the categories, which is why it sits slightly apart from the parallelogram family.