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 → Measurement ↓


Length


Length is one of the most basic concepts in mathematics and everyday life. When we talk about length, we talk about the length of something. It can be the length of a rope, the height of a tree, or even the distance between two places. In this explanation, we will learn the concept of length, how to measure it, and why it is important.

What is the length?

Length is a measure of distance. It tells us how long, high, or far away something is. We use length to describe the size of objects or the space between objects. For example, a pencil may be 7 inches long, a building may be 100 feet high, and the distance between two cities may be 300 miles.

Let's visualize this with a straight line. The |----|----| part of the line is its length.

,

In this example, the length of the line segment is the distance from the first | to the last |.

Units of length

We use units to measure length. Units are standard quantities used to specify measurements. When measuring length, some common units include:

  • Inch (in): Often used in the United States to measure small objects.
  • Feet (ft): One foot is equal to 12 inches.
  • Yard (yd): One yard is equal to 3 feet.
  • Mile (mi): Used to measure long distances.
  • Centimetre (cm): Commonly used in most countries around the world.
  • Meter (m): One meter is equal to 100 centimeters.
  • Kilometre (km): Used to measure long distances in many parts of the world.

How to measure length

To measure length, you can use different tools depending on what you're measuring:

  • Ruler: A small tool often with markings in inches and centimeters, good for measuring things like books or chairs.
  • Measuring tape: A flexible ruler, usually long, used to measure things such as rooms and furniture.
  • Yardstick: A 3-foot-long ruler that helps measure large objects.

Example of measuring length

Let's say you have a book and you want to know how long it is. You can use a ruler to do this. Simply place the ruler at one end of the book and read the number at the other end. If the book ends at the "12" mark on your ruler, then the book is 12 inches long.

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Length comparison

Comparing lengths is also an important part of understanding length. You will want to know how one length compares to another, such as which length is longer or shorter.

For example, let's compare two sticks. If one stick is 8 inches long and the other is 10 inches long, you can say that the second stick is longer. A simple way to look at this is:

8 inch 10 inches

Adding and subtracting lengths

Sometimes, you need to add or subtract lengths. For example, if you have one strand that's 5 inches long and another strand that's 7 inches long, you add them together to find the total length:

5 inches + 7 inches = 12 inches

Also, if you want to know how much longer the second piece is than the first piece, you subtract:

7 inches - 5 inches = 2 inches

Estimating the length

There may be times when you don't have a ruler and you need to estimate the length of something. Estimating means that you make an educated guess. For example, if you know that your thumb is about 2 inches long, you can use that to estimate the length of small objects by seeing how many "thumb lengths" fit along it.

Practice guessing

Pick up an object and estimate how long it is using a known measurement of your body, such as your arm or leg span. Then, use a ruler to see how close you were!

your guess Real

Use of length in real life

Understanding length is very helpful in real life. For example:

  • For building construction, builders need to have accurate knowledge of the length and width of the material.
  • Fashion designers cut clothes to length to make them fit well.
  • Farmers measure the length to plant crops in evenly spaced rows.

Imagine a farmer is measuring a plot of land 100 meters long to plant corn. Knowing the dimensions of the field helps in planning the number of seeds to be sown.

Conclusion

Length is an important and useful concept. It helps us understand the size and distance of things around us. By measuring length accurately, we can compare objects, add and subtract dimensions, and apply this knowledge in practical scenarios.


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