What is The Difference in Lengths?

S1-SA4-0402

Grade Level:

Class 3

All STEM domains, Finance, Economics, Data Science, AI, Physics, Chemistry

Definition

What is it?

The 'difference in lengths' means finding out how much longer one object is compared to another, or how much shorter one object is than another. It helps us compare two lengths and see how far apart they are.

Simple Example

Quick Example

Imagine you have two pencils. One is 15 cm long, and the other is 10 cm long. To find the difference in their lengths, you subtract the shorter length from the longer length. So, 15 cm - 10 cm = 5 cm. The difference is 5 cm.

Worked Example

Step-by-Step

PROBLEM: A cricket bat is 80 cm long. A wicket is 71 cm long. What is the difference in their lengths?
--- STEP 1: Identify the two lengths given. Length of cricket bat = 80 cm. Length of wicket = 71 cm.
--- STEP 2: To find the difference, we subtract the smaller length from the larger length.
--- STEP 3: Write down the subtraction problem: 80 cm - 71 cm.
--- STEP 4: Perform the subtraction.
80
- 71
----
9
--- ANSWER: The difference in their lengths is 9 cm.

Why It Matters

Understanding differences in length is crucial in many fields! Engineers use it to design buildings and bridges, ensuring parts fit perfectly. Doctors use it to measure growth or compare body parts. Even fashion designers use it to make clothes that fit different body sizes.

Common Mistakes

MISTAKE: Always subtracting the first number from the second, even if it's smaller. | CORRECTION: Always subtract the smaller length from the larger length to get a positive difference.

MISTAKE: Forgetting to include the units (like cm, m, km) in the answer. | CORRECTION: Always write the unit of measurement with your final answer to make it clear.

MISTAKE: Mixing different units (e.g., subtracting cm from meters without converting). | CORRECTION: Before finding the difference, make sure both lengths are in the same unit. Convert one if needed.

Practice Questions

Try It Yourself

QUESTION: Your school playground is 50 meters long. Your friend's playground is 42 meters long. What is the difference in their lengths? | ANSWER: 8 meters

QUESTION: A tailor has a piece of cloth that is 120 cm long. He cuts off a piece that is 75 cm long. How much cloth is left? (Hint: This is also finding a difference!) | ANSWER: 45 cm

QUESTION: A rope is 3 meters and 20 cm long. Another rope is 2 meters and 80 cm long. What is the difference in their lengths in centimeters? | ANSWER: 40 cm

MCQ

Quick Quiz

A table is 150 cm long and a bench is 95 cm long. What is the difference in their lengths?

55 cm

245 cm

65 cm

45 cm

The Correct Answer Is:

To find the difference, subtract the smaller length from the larger one: 150 cm - 95 cm = 55 cm. Options B, C, and D are incorrect calculations.

Real World Connection

In the Real World

When you buy clothes online, companies like Myntra or Ajio often provide size charts with measurements. Knowing how to find the difference in lengths helps you compare your body measurements to the clothing size to ensure a good fit, avoiding returns and exchanges.

Key Vocabulary

Key Terms

LENGTH: How long something is | DIFFERENCE: The result of subtracting one number from another | COMPARE: To look at two or more things to see how they are similar or different | UNIT: A standard amount used for measuring (e.g., cm, meter)

What's Next

What to Learn Next

Great job learning about the difference in lengths! Next, you can explore 'Adding and Subtracting Lengths with Different Units'. This will help you solve more complex problems where you need to convert units before finding sums or differences.