Comparing and Measuring Weight for Primary 1

Weight

Performance Objectives

By the end of the lesson, students should be able to:

1. Compare the weights of some common objects in the school using the terms light and heavy.

What is Weight?

Weight tells us how heavy or light an object is. Some objects are heavy, and some objects are light.

When a person lifts an object, they can feel if it is heavy or light. Heavy objects are harder to lift, while light objects are easier to lift.

Lifting Objects to Feel Their Weight

One way to understand weight is by lifting different objects. When you lift a school bag full of books, it feels heavy. When you lift a single pencil, it feels light.

This feeling helps us to know which objects are heavy and which are light. It helps us to estimate their weight.

Estimating and Comparing Weights

Estimating weight means making a good guess about how heavy or light an object is, usually by lifting it or looking at its size. Comparing weights means finding out which of two or more objects is heavier or lighter.

In the school, many objects can be compared. For example, a textbook is usually heavier than an exercise book. A school desk is heavier than a chair. A bucket of water is heavier than an empty bucket.

Comparing Objects Using “Heavy” and “Light”

When comparing two objects, one object can be heavier than the other, or one can be lighter than the other. Sometimes, two objects can have almost the same weight.

To compare objects, a person can lift one object in each hand. The object that pulls the hand down more is the heavier one. The object that feels easier to hold up is the lighter one.

Examples of comparing objects in the school include:

1. A school textbook is heavier than a ruler.
2. A school chair is lighter than a school table.
3. A full water bottle is heavier than an empty water bottle.
4. A blackboard duster is lighter than a stapler.
5. A school bag is heavier than a lunch box.

Using a Weight Balance to Compare Weight

A weight balance, also called a balance scale, is a tool that helps to compare the weights of objects more accurately. It has two pans or trays. When objects are placed on the pans, the heavier object makes its pan go down, and the lighter object’s pan goes up.

A see-saw works like a large balance scale. When a heavier child sits on one side of a see-saw, that side goes down, and the lighter child’s side goes up.

How to Use a Balance Scale to Compare Objects

Using a balance scale helps to see which object is heavier or lighter without just guessing.

The procedure involves the following steps:

1. Place the balance scale on a flat, steady surface.
2. Take two different objects that you want to compare, for example, a pencil and an eraser.
3. Carefully place the pencil on one pan of the balance scale.
4. Carefully place the eraser on the other pan of the balance scale.
5. Observe which pan goes down. The object on the pan that goes down is heavier. The object on the pan that goes up is lighter.
6. If both pans stay level, it means the objects have almost the same weight.