Tricky Bags


This unit comprises 5 stations, which involve the students developing an awareness of the attributes of volume and mass. The focus is on the development of the language of measurement.

Achievement Objectives
GM1-1: Order and compare objects or events by length, area, volume and capacity, weight (mass), turn (angle), temperature, and time by direct comparison and/or counting whole numbers of units.
Specific Learning Outcomes
  • Push, pull, lift and handle objects in order to become aware of mass.
  • Compare 2 masses by pushing and lifting.
  • Pack materials and fill containers.
  • Pour liquids from and into containers.
Description of Mathematics

Early experiences must develop an awareness of what mass is, and of the range of words that can be used to describe it. A mass needs to be brought to many students’ attention as it is not an attribute that can be seen. They should learn to pick up and pull objects to feel their heaviness. Initially young students describe objects as heavy or not heavy. They gradually learn to compare and use more meaningful terms such as lighter and heavier.

As with other measures, students require practical experience to begin to form the concept of an object taking up space. Students need lots of experiences of filling and emptying containers with sand and water. They need to have pouring experiences with containers of similar shape but different capacity and vice versa. They also need to fill containers with objects and build structures with blocks. The use of language such as: it’s full, it’s empty, there’s no space left and it can hold more, focus attention on the attribute of volume. The awareness of the attribute of volume is extended as comparisons of volume are made at the next stage.

The stations may be taken as whole class activities or they may be set up as "centres" for the students to use. We expect that many 5 year-olds will already be aware of the attributes of volume and mass. For them these may be useful learning through play activities.

Opportunities for Adaptation and Differentiation

The learning opportunities in this unit can be differentiated by providing more support or challenge to students. For example:

  • In session 1 and 2 increase the challenge by asking students to order three bags/cartons by mass.

The measuring activities in this unit can be adapted to use objects that are part of your students everyday life.  For example:

  • In session 1 compare the mass of students’ backpacks. 
  • In session 3 replace The Three Bears with another story that has characters with different sized “appetites”, that is popular with your students (e.g. Peppa, George and Daddy Pig).
Required Resource Materials
  • Session 1: Two bags, supermarket reusable bags
  • Session 2: Two cartons, chart paper
  • Session 3: Paper or light card, popcorn
  • Session 4: Paper cups, beans, containers
  • Session 5: Book Corner

Session 1: Tricky bags

In this activity we investigate two bags that look the same but one empty and the other is filled with books.

  1. Display the two bags for the students to see.
    Are these bags the same or different?
    How do you know?
    Are you sure?
  2. If no one suggests looking in the bags or lifting them ask for two volunteers to lift a bag each and describe what they feel. List the words that they use.
  3. Let other students lift the bags and give their description.
  4. Give pairs of students two supermarket bags and ask them to make up their own "tricky bags"
  5. Let the students share their tricky bags with other pairs of students. Remind them to describe what the bag feels like when they lift it.
    Can you guess by just looking which is heavy?

Session 2: Push and Pull

In this activity we push and pull objects to see which feels heavier.

  1. Show the students two large cartons.
    Are these cartons the same or different?
    How do you know?
    Are you sure?
    How could you find out?
  2. If this activity has followed from the tricky bags activity you would expect the students to suggest that they lift the cartons. Tell the students that the cartons are too large to be lifted and ask if they could think of another way of comparing them.
    The cartons are too large for you to lift safely. Can you think of another way of finding out how heavy they are?
  3. Let the students take turns pushing or pulling the cartons.
    Do you think they are the same?
    Why? Why not?
    Which carton is heavier? How do you know?
  4. Discuss the objects that the students have seen being pushed or pulled rather than lifted. For example: beds, tables, television cabinet, couches.
  5. Ask the students to draw a picture of one of these objects. Attach them to a chart of "Pushes and Pulls".

Session 3: Popcorn for the 3 bears

In this activity we make popcorn containers for the Three Bears.

  1. Read or tell the story "The Three Bears" to the students. When you have finished tell the students that the bears are going to the movies and want to buy some popcorn.
    What size popcorn would Father Bear want?
    What size popcorn would Mother Bear want?
    What size popcorn would Baby Bear want?
  2. Tell the students that they are going to make popcorn containers for the Bears popcorn. Show the students how to make popcorn cones by rolling a piece of paper or light card.
  3. Ask the students to make containers for the Three Bears popcorn.
  4. As a class look at the popcorn cones made.
    How could we check if Father Bears holds the most?
  5. Give the students popcorn to pour between the containers to check.

Session 4: Fill it up

In this activity we pour water (or beans) between containers and guess how high up the water will go.

  1. Show the class a cup full of beans and an empty ice-cream container.
    What do you think will happen if I pour the beans into the ice-cream container?
    How far will it fill up?
  2. Check and discuss
    Did you guess correctly?
    Is the container full?
    Is it empty?
  3. Give each student a cup full of beans. Put several containers of varying sizes around the room. Ask the students to pour their beans into the containers, first guessing how high up they think the beans will go.

Session 5: Book corner

In this activity we look at some picture books that could be read to the students to reinforce measuring language associated with volume and mass.

  1. Who sank the Boat? Pamela Allen. (1983). Putman Publishing Group
  2. Teddy bears go shopping.  Gretz, S. (1985) Scolastic.
  3. Goldilocks and the three bears
  4. Phoebe and the hot water bottles. Furchgolt, T., and Dawson, L. (1980) Collins.
  5. Something absolutely enormous. Wild, M. (1984) Ashton Scholastic.
  6. Mr Archimedes' bath.  Allen, P. (1985) Nelson.

More titles and measurement specific activities are available on the Level 1 Measurement Picture Books page.

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Level One