Measurement

Measurement is a way of knowing the size, length or quantity of something. We measure all kinds of things in our everyday lives, such as time, temperature, length, weight and volume. Understanding measurement helps us make decisions such as buying the right size of clothes or the right amount of food. In Class 5, you learn more about measurement in different fields. Let's explore it in detail.

Length

Length is a measurement that refers to the length of an object from one end to the other. It can be measured in different units such as millimetres (mm), centimetres (cm), metres (m) and kilometres (km). To measure length, we usually use a ruler, meter stick or measuring tape.

Example 1: Measuring table

Suppose you have a table. You want to know its length. Ask someone to hold one end of the tape at one end of the table. Now, pull the tape to the other end. Read the number at the end of the table on the tape. This is the length of the table!

Units of length

• Millimeters (mm): Very small measurement. Think about the thickness of a credit card.
• Centimeter (cm): 10 mm makes 1 cm. A paperclip is about 3 cm long.
• Meter (m): 100 cm makes 1 meter. A standard door is about 2 meters high.
• Kilometer (km): 1000 meters make 1 km. It is used to measure long distances like roads.

1 kilometer = 1000 meters
1 meter = 100 centimeters
1 centimeter = 10 millimeters

Example 2: Converting length

If a pencil is 150 millimetres long, what is its length in centimetres?

150 mm = 150/10 = 15 cm

So, the pencil is 15 cm long.

To change a larger unit into a smaller unit you multiply. To change a smaller unit into a larger unit you divide.

Mass or weight

Mass is the heaviness of something. It is often measured in grams (g) and kilograms (kg). We use scales to measure mass.

Example 1: Weighing fruit

If you want to weigh an apple, put it on the scales. If the number is 150 g, it means the apple weighs 150 g.

Units of mass

• Gram (g): A small unit of mass. A paperclip weighs about 1 gram.
• Kilogram (kg): 1000 grams make 1 kilogram. A textbook weighs approximately 1 kilogram.

1 kilogram = 1000 grams

Example 2: Converting weights

If you have 2500 grams of sugar how many kilograms is it?

2500 g = 2500/1000 = 2.5 kg

So, you have 2.5 kg of sugar.

Volume

Volume is the space an object occupies. It is often measured in milliliters (mL) and liters (L). Volume can be measured with measuring cups, jugs, and beakers.

Example: Measuring water with a jug

If you pour water into a measuring jug and the water level is 500 ml, it means that there is 500 ml of water in the jug.

Units of volume

• Millilitre (mL): A small unit of volume. A teaspoon can hold about 5 mL of liquid.
• Liter (L): 1000 milliliters make 1 liter. A large soda bottle is usually 2 liters.

1 liter = 1000 milliliters

Converting volumes

If a bottle contains 1.5 liters of juice, how many milliliters is it?

1.5 L = 1.5 * 1000 = 1500 mL

So, the bottle contains 1500 ml of juice.

Time

Time measures how long things last. We use clocks and calendars to measure time. Units of time include seconds, minutes, hours, days, and years.

Units of time

• Second (s): The basic unit of time.
• Minute (min): 60 seconds make 1 minute.
• Hour (h): 60 minutes make 1 hour.
• Day: 24 hours together make one day.
• Year: 365 days make one year.

1 minute = 60 seconds
1 hour = 60 minutes
1 day = 24 hours
1 year = 365 days (or 366 in a leap year)

Example: Time conversion

If an event lasts 3 hours 30 minutes, how many minutes will it be?

3 hours = 3 * 60 = 180 minutes
180 minutes + 30 minutes = 210 minutes

The event lasts for 210 minutes.

Temperature

Temperature tells us how hot or cold something is. We measure temperature in degrees Celsius (°C) or degrees Fahrenheit (°F).

When you measure temperature, you use a thermometer. If the thermometer shows 20°C, it means the temperature is 20°C.

Scale conversion

To convert Celsius to Fahrenheit:

°F = (°C * 9/5) + 32

To convert Fahrenheit to Celsius:

°C = (°F - 32) * 5/9

Example: Temperature conversion

If the temperature outside is 20°C, what will be the temperature in Fahrenheit?

°F = (20 * 9/5) + 32 = 68°F

So 20°C = 68°F.

Perimeter and area

Perimeter is the distance around the edge of a shape. We often measure it in units like meters and centimeters.

Area is the size of a surface. We measure it in square units such as square metres m2 or square centimetres cm2.

Calculating perimeter

If you have a rectangle, you can find its perimeter by adding the lengths of the four sides:

Perimeter = 2 * (length + width)

Example: Perimeter of a rectangle

If a rectangle is 5 m long and 3 m wide, what is its perimeter?

Perimeter = 2 * (5 + 3) = 2 * 8 = 16 m

The perimeter of the rectangle is 16 meters.

Calculating the area

For a rectangle, the area is the length times the width:

Area = length * width

Example: Area of a rectangle

If a rectangle is 5 m long and 3 m wide, what is its area?

Area = 5 * 3 = 15 m2

The area of the rectangle is 15 square meters.

Conclusion

Measurement is a fundamental concept that applies to many aspects of our lives, helping us measure the world around us. Understanding measurements of length, mass, volume, time, temperature, perimeter, and area equips students with practical skills useful in everyday life. Practicing measurement activities increases accuracy and understanding in practical applications, fostering a greater appreciation for precise, quantitative descriptions of the world.

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