104
Mass and the kilogram
Textbook Part 3, pp. 62–63
GoalCompare mass; meet the kilogram; weigh things on scales.
New words
mass (weight) · massakilogram (kg) · kilogramm (kg)scales · taroziheavy / light · og‘ir / yengil
Explanation
How heavy something is is called its mass. Mass is measured in kilograms: 1 kg. On a balance scale the heavier side goes down. Masses can be added and subtracted too: 5 kg + 1 kg = 6 kg.
Worked examples
5 kg of fruit and 1 kg of flour were bought at the supermarket: 5 + 1 = 6 kg.
An apple is heavier than a strawberry; a banana is heavier than a cherry.
Class activity
“Hand scales”: a child holds two objects and guesses which is heavier; then they are checked on a kitchen scale.
Practice
1
Which is heavier: a strawberry or an apple?
The apple
2
5 kg + 6 kg = ?
11 kg
3
6 kg − 5 kg = ?
1 kg
4
A watermelon is 7 kg and a melon 4 kg. How much heavier is the watermelon?
3 kg