3rd Class Mathematics Measurement Length, Weight and Capacity Measurement Weight

LEARNING OBJECTIVES

This lesson will help you to:—

• weigh objects using nonstandard units.
• relate objects with their weight.
• learn about standard units of weight like gram (gm) and kilogram (kg).
• choose appropriate standard unit of weight.

REAL LIFE EXAMPLES

• Weighing objects helps us to know whether the object is heavy or light.
• Fruit sellers and vegetable sellers use weighing balance to weigh fruits and vegetables.
• Doctors weigh their patients before prescribing any medicine to them especially children.
• Grocery store sells items like sugar, wheat flour (atta), tea, etc according to their weights.
• Cooking is done by measuring of weight of ingredients.

AMAZING FACTS

• The adult human brain weighs about 1300-1400 gm.
• The average person’s skin weighs twice as much as their brain.

QUICK CONCEPT REVIEW

How many types of weighing devices have you seen?

Check out the different types of weighing devices given

Below: They all are weighing scale. They are used for different purposes.

1. To weigh small babies
2. To weigh body weight
3. To weigh things like vegetables, groins, etc.
4. To weigh junk or various other things
5. At shops
6. At gyms even at places where big sacks are weighed.

Examples:-

1. A paperclip weighs about 1 gram.

Try weighing a safety pin!

2. You can weight your body weight using weighing machine.

Try to measure your weight!

3. Body builders lift heavy weights every day to maintain their body.

Can you guess the weights they lift?

MEASURING WEIGHT

SHORTCUT TO PROBLEM SOLVING

1. Always start from "O" while using weighing balance.
2. Gram (gm) is used to weigh lighter objects.
3. Kilogram (kg) is used to measure heavier objects.

MASS CONVERSION FACTORS

1 centigram (Cg) = 10 milligram (mg)

1 decigram (dg) = 10 centigram (Cg)

1 gram (gm) = 10 dg = 1000 mg

1 dekagram (dag) = 10 gram

1 hectogram (hg) = 10 dekagram

1 kilogram (kg) = 1000 gram

HISTORICAL PREVIEW

• The kilogram is the base unit of mass in the International System of Units.
• The Kilogram is equal to mass of one liter of water.

Misconcept/Concept

Misconcept: The object which looks bigger in size is heavier than the object which looks smaller in size.

Concept: The size of an object is not linked with its weight.

Misconcept: While using a weighing balance, the reading of the scale start from ‘1’ since the counting of number starts term ‘1’.