Grade 3
  1. Number Sense and Numeration  1.1. Understanding Numbers  1.1.1. Reading and Writing Numbers up to 10,000  1.1.2. Place Value up to Thousands  1.1.3. Comparing and Ordering Numbers  1.1.4. Rounding Numbers to the Nearest Ten and Hundred  1.1.5. Skip Counting by 2s, 5s, 10s, and 100s up to 1,000  1.2. Operations with Whole Numbers  1.2.1. Addition and Subtraction up to 1,000  1.2.2. Multiplication Facts (up to 10 x 10)  1.2.3. Division Facts (up to 100)  1.2.4. Multiplication as Repeated Addition  1.2.5. Division as Equal Sharing  1.2.6. Word Problems with Addition, Subtraction, Multiplication, and Division  1.3. Estimation  1.3.1. Estimating Sums and Differences  1.3.2. Estimating Products and Quotients  1.4. Understanding Even and Odd Numbers
  2. Fractions and Decimals  2.1. Understanding Fractions  2.1.1. Identifying and Representing Fractions  2.1.2. Fractions of a Whole and Part of a Set  2.1.3. Comparing and Ordering Fractions with Like Denominators  2.1.4. Equivalent Fractions  2.1.5. Simple Fraction Word Problems  2.2. Introduction to Decimals  2.2.1. Tenths and Hundredths as Decimals  2.2.2. Relationship between Fractions and Decimals
  3. Measurement  3.1. Length  3.1.1. Measuring in Centimeters and Meters  3.1.2. Comparing and Ordering Lengths  3.1.3. Estimating Lengths  3.1.4. Converting Between Centimeters and Meters  3.2. Mass  3.2.1. Measuring in Grams and Kilograms  3.2.2. Estimating and Comparing Mass  3.3. Capacity  3.3.1. Measuring in Milliliters and Liters  3.3.2. Estimating and Comparing Capacity  3.4. Time  3.4.1. Telling Time to the Nearest Minute  3.4.2. Calculating Elapsed Time  3.4.3. Using a Calendar  3.4.4. Understanding A.M. and P.M.  3.5. Area and Perimeter  3.5.1. Calculating Perimeter of Simple Shapes  3.5.2. Estimating and Measuring Area of Shapes  3.5.3. Finding Area by Counting Squares
  4. Geometry  4.1. Properties of Shapes  4.1.1. Identifying 2D Shapes (Triangles, Quadrilaterals, Circles, etc.)  4.1.2. Identifying 3D Shapes (Cubes, Spheres, Cylinders, etc.)  4.1.3. Describing Attributes of 2D and 3D Shapes  4.1.4. Recognizing Parallel and Perpendicular Lines  4.2. Symmetry and Transformations  4.2.1. Recognizing Lines of Symmetry  4.2.2. Identifying Flips, Slides, and Turns  4.3. Angles  4.3.1. Understanding Right Angles  4.3.2. Comparing Angles (Acute, Right, Obtuse)
  5. Data Management and Probability  5.1. Data Collection and Organization  5.1.1. Collecting Data using Surveys and Experiments  5.1.2. Organizing Data using Tally Charts and Tables  5.2.1. Creating and Interpreting Pictographs  5.2.2. Creating and Interpreting Bar Graphs  5.2.3. Reading Simple Line Graphs  5.3. Probability  5.3.1. Understanding Basic Probability Terms (Certain, Possible, Impossible)  5.3.2. Predicting Outcomes  5.3.3. Simple Probability Experiments
  6. Patterns and Algebra  6.1. Patterns  6.1.1. Identifying and Extending Numeric Patterns  6.1.2. Identifying and Extending Shape Patterns  6.1.3. Creating Patterns Using Rules  6.2. Introduction to Algebra  6.2.1. Understanding Variables as Unknowns  6.2.2. Solving Simple Addition and Subtraction Equations  6.2.3. Using Patterns to Solve Problems
  7. Problem-Solving Skills  7.1. Strategies for Problem-Solving  7.1.1. Using Pictures or Diagrams  7.1.2. Identifying Patterns in Problems  7.1.3. Making Organized Lists  7.1.4. Guessing and Checking  7.1.5. Using Logical Reasoning  7.1.6. Breaking Down Problems into Steps

Grade 3 → Geometry → Properties of Shapes ↓


Identifying 2D Shapes (Triangles, Quadrilaterals, Circles, etc.)


In geometry, understanding and recognising 2D shapes is one of the fundamental skills students need to develop. In Grade 3, we focus on recognising a range of basic geometric shapes, also known as 2D shapes. These include triangles, quadrilaterals, circles and others. The aim is to explore their characteristics, such as sides, angles and symmetry, which helps to understand what each shape looks like and behaves like.

What are 2D shapes?

2D shapes or two-dimensional shapes are flat and can only be measured in two ways: length and width. An easy way to think about them is to imagine a piece of paper that is flat. You can draw 2D shapes on that paper. They do not have depth like 3D shapes such as cubes or spheres.

Triangle

A triangle is a 2D shape with three sides and three angles. There are many types of triangles and we classify them based on their sides and angles.

Types of triangles

  • Equilateral triangle: The three sides are the same length, and the three angles are equal. Each angle in an equilateral triangle is 60 degrees.
  • Isosceles triangle: At least two sides are of equal length, and the angles opposite to those sides are also equal.
  • Scalene triangle: All sides and angles are different. No sides are the same length, and no angles are equal.
  • Right angle: One of its angles is exactly 90 degrees.
<svg width="100" height="100"> <polygon points="10,90 50,10 90,90" stroke="black" stroke-width="2" fill="none"/> </svg>

Quadrilateral

Quadrilaterals are 2D shapes that have four sides and four angles. There are many different types of quadrilaterals. Let's take a look at some of the common types.

Types of quadrilaterals

  • Square: All four sides are equal length, and each angle is a right angle (90 degrees).
  • Rectangle: Opposite sides are equal in length and each angle is a right angle.
  • Rhombus: All sides are the same length but the angles are not 90 degrees.
  • Parallelogram: Opposite sides are parallel and equal in length.
  • Trapezium: Only one pair of sides is parallel.
<svg width="100" height="100"> <rect x="10" y="20" width="80" height="50" stroke="black" stroke-width="2" fill="none"/> </svg>

Circles

A circle is a 2D shape where all points on its boundary are the same distance from its center. This distance is known as the radius, and the line segment through the center connecting two points on the boundary is the diameter, which is twice the radius.

<svg width="100" height="100"> <circle cx="50" cy="50" r="40" stroke="black" stroke-width="2" fill="none"/> </svg>

Polygon

Polygons are closed shapes with straight sides. Triangles and quadrilaterals are types of polygons. However, there are polygons with more than four sides.

Examples of polygons

  • Pentagon: A polygon with five sides.
  • Hexagon: A polygon with six sides.
  • Octagon: A polygon with eight sides.
<svg width="100" height="100"> <polygon points="50,15 90,50 70,90 30,90 10,50" stroke="black" stroke-width="2" fill="none"/> </svg>

Properties of 2D shapes

There are a few properties that can be very helpful when identifying these shapes:

Number of sides

The number of sides is a basic and quick way to identify a shape.

Triangle: 3 sides Quadrilateral: 4 sides Pentagon: 5 sides Hexagon: 6 sides

Angles

Each figure has different types of angles. For example, the sum of the angles of a triangle is 180 degrees, while the sum of the angles of a quadrilateral is 360 degrees.

Symmetry

Some shapes, such as circles and squares, have lines of symmetry. A line of symmetry divides a shape into two equal parts. A shape is symmetrical if it can be folded along a line so that the two halves match exactly.

Square: 4 lines of symmetry Circle: infinite lines of symmetry

Interactive exercises

To understand these shapes better, draw them yourself using a ruler and compass or software that lets you draw. Look at the objects around you; you'll find that 2D shapes are everywhere.

Conclusion

Recognizing and understanding 2D shapes involves recognizing their features such as sides, angles, and symmetry. Whether it is a triangle, quadrilateral, or circle, each shape has unique features that help students classify and understand them better. This knowledge lays the foundation for more complex geometric concepts in the future.


Grade 3 → 4.1.1


U
username
0%
completed in Grade 3

← Prev (4.1)
Properties of Shapes
Next (4.1.2) →
Identifying 3D Shapes (Cubes, Spheres, Cylinders, etc.)

Comments 



Identifying 2D Shapes (Triangles, Quadrilaterals, Circles, etc.)

https://www.buddymath.com/g3/4.1.1?bmal=en