Mass

Tip of the day: If you want to lose weight, go to the moon.

Mass is a measure of the amount of matter in an object, whereas weight is the force of gravity acting on that mass. When astronauts orbit the earth in the space shuttle, their weight is less than it is on earth but their mass does not change. Hence, it is accurate to refer to mass instead of weight.


In Primary One, the children were introduced to the concept of mass with 2 objects as an example:


Say, I hold a brick in one hand and a basketball in the other and ask "Which is heavier?" From their experience, children will likely know that although the ball is larger in size, the brick is heavier. Then, I will proceed to ask the class to name some things that are heavier and light. These ideas were further developed as the children hold objects and feel the pull of gravity. In most cases, the masses of two objects cannot be compared by sight, they must be held to determine which is heavier. Simply, I do not randomly choose the objects. Otherwise, some choices are quite obvious e.g. a piece of paper and a basketball.


This week, we will cover the standard units for measuring mass - kilogram (kg) and gram (g). At home, children should look for products that are packaged or sold by mass. (e.g. a cake mix, a box of cereal, a candy bar or a bag of apples.)


Avoid measuring bottled drinks or canned beverages as they are more closely related to the topic volume.


Avoid saying kg as 'k-g'. Pronounce kg as kilogram because we don't pronounce g as 'g', we say gram.




Learning objectives: (there are some more!)

• read a scale which shows '1 kg', 'less than 1 kg' or 'more than 1 kg'
• find the mass of an object in kg using the balance with 1-kg masses
• compare the masses of objects and tell which is heavier or lighter

Note the smaller parts within the scale? I will have a separate post about it.




Thank you.