Lesson 10 — Activity 2: Measuring Mass



Getting Ready


Just as with distances, you measure masses every day without really thinking about it. Remember these questions that you considered in the introduction to the last activity?

Can your truck hold a really heavy load of gravel? How big is that newborn calf?

These were questions regarding mass. Even though it is common for people to estimate these masses, it is important to use the proper units so that others can understand what you are talking about.



Think about This:

The metric system measures not weight but mass.


Remember that mass is the amount of matter in an object. Weight is a measure of how heavy an object is.

   

Image courtesy of Pixabay


Small amounts of mass can be measured using a balance scale . A balance scale is a device that has two pans or trays with a balance point (fulcrum) in the middle.



 

To measure the mass of an object, the object is placed on one pan and standard masses are placed on the other pan until the pans balance each other. The mass of the object is the sum of the standard masses on the other pan.

Image courtesy of Pixabay

The three units of measurement that we use the most when talking about mass are the milligram, the gram, and the kilogram. One more unit that you may come across is the tonne.


  • A milligram (mg) is a very small unit used to measure mass.
  • Ingredients in medications are measured and listed in milligrams.



Image courtesy of iStock

  • Other things that can be measured in milligrams include a raindrop or a grain of rice.



Image courtesy of Pixabay
 

  • A raindrop averages about 200 mg; a grain of rice averages about 29 mg.

  • A gram (g) is 1/1,000 of a kilogram. We use grams to weigh such things as small portions of food or very light objects.

  • A nickel weighs about 5 grams.



Image courtesy of ADLC
 

  • Other things that can be measured in grams include cereal ingredients or the amount of flour used in a recipe.


           
Image courtesy of Pixabay

  • A kilogram (kg) is 1,000 grams. It is used to measure most average sized things such as furniture, animals, people, and motorbikes.

  • Scales measure our weight using kilograms. An adult weighs about 70 kg. How much do you weigh?

Image courtesy of Pixabay



               

Image courtesy of Pixabay

  • A tonne (t) is the largest unit of mass that is commonly used. A tonne is 1,000 kg. Trucks, tanks, ships, and airplanes are weighed in tonnes.
  • The average car has a mass of about 1 tonne.   


Try This:

Practise choosing the appropriate unit of measure for the items below.


If you wanted to measure the weight of a newborn calf, you would choose:

  • milligrams (mg)
  • grams (g)
  • kilograms (kg)
  • tonnes (t)


 The most appropriate unit would be kilograms (kg).



Image courtesy of Pixabay

 
Image courtesy of Pixabay

If you wanted to measure the mass of a chocolate bar, you would choose:

  • milligrams (mg)
  • grams (g)
  • kilograms (kg)
  • tonnes (t)


 The most appropriate unit would be grams (g).



  Self-check!

Try this!

Try this activity to further practice determining the unit of measure you would use to measure the mass of an object


Fill in the blanks with one of these units of mass (answers may be selected more than once).

  • milligrams

  • grams

  • kilograms

  • tonnes


A cruise ship would be weighed in ______.


A pencil would be weighed in ______.


A person would be weighed in ______.


A bag of chocolate chips would be weighed in ______.


A truck load of fertilizer would be weighed in ______.


If you only needed a small amount fo salt in a recipe, it would be weighed in ______.


A piece of writing paper would be weighed in ______.


A big dictionary would be weighed in ______.


A cow would be weighed in ______.


Digging Deeper

Click on the Play button below to watch a video to learn more about measuring the mass of objects.




Digging Deeper

Click here to try the Taking Measures — Weight Game.