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 → Angles ↓


Understanding Right Angles


Angles are everywhere in the world of geometry. From the corners of a book to the way the hands on a clock cross each other. To better understand angles, one of the most important types of angles is the "right angle." Let's use simple terms and clear examples to learn what makes a right angle special.

What is the angle?

An angle is formed when two lines meet at a point. This point is called the "vertex" of the angle. Imagine if two rays of light meet at a point; they spread out in different directions from that point, forming an angle.

Peak

This is an angle.

What is a right angle?

A right angle is a special kind of angle. When two lines meet to form an angle that looks like the corner of a square, it is called a right angle. It measures exactly 90 degrees. Right angles are everywhere, from the corners of a book to street intersections.

90°

This is a right angle.

Characteristics of right angles

Right angles are unique because:

  • They measure exactly 90 degrees.
  • They look like the letter L.
  • These are often marked in diagrams with a small square at the top.

Where do we see right angles?

Right angles are all around us. Here are some examples:

  • The corner of a piece of paper.
  • Where two roads meet at right angles.
  • Corner of computer screen or TV.
  • The edges where the walls of a room meet.
  • The base of a triangle when it stands upright.

Visualization of right angle

To better understand right angles, we can visualize them using squares and rectangles. Both shapes have four right angles.

right angles!

In the above figure, each corner of the square represents a right angle.

Right angles in math problems

We encounter right angles in many math problems, especially in geometry. Here are some simple problems involving right angles:

Example 1: What is the degree measure of a right angle?

Solution: The measure of a right angle is 90 degrees.

Example 2: How many right angles are there in a rectangle?

Solution: A rectangle has four corners, and each corner is a right angle, so there are 4 right angles.

Practice with right angles

To practice, try to find right angles around you. Look at things like the corners of books or the edges of tables. You can also draw right angles using paper and pencil. Practice drawing them to become more familiar with these angles.

When you draw a right angle, first draw a straight line. Then, draw another line upward from any point on that line so the two lines look like a capital letter "L."

Using tools to draw right angles

There are tools that can help us measure and construct right angles:

  • Ruler: Used to draw straight lines.
  • Protractor: Used to measure angles. A right angle on a protractor will measure 90 degrees.
  • Set square: A triangular tool with at least one right angle, often used in carpentry and drafting.

Conclusion

We use right angles every day, without even realizing that we understand them. Right angles are important to recognize and understand because they are the basis for many figures and shapes in geometry. Knowing how to find and draw right angles can help you solve many practical problems. From figuring out whether a room corner is a right angle to understanding squares and rectangles, right angles play an important role in the world of geometry.

So keep an eye out for right angles around you, practice making them, and try to identify them in different objects. You'll soon see that right angles are all around you!


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Understanding Right Angles

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