E2.4 Compare, estimate, and measure the mass of various objects, using a pan balance and non-standard units.
Activity 1: Which Object Has the Greatest Mass?
Goal
In this activity, students estimate, sort, and order different types of balls to determine their mass.
Materials
Variety of balls (e.g., soccer ball, basketball, volleyball, beach ball, tennis ball, golf ball, baseball, sponge ball, rubber ball, ping pong ball)
Note: It is important that at least one small ball has a greater mass than a larger ball.
Instructions
Have students sit in a circle. Place a variety of balls in the centre of the circle. Have students examine them carefully without touching them.
Ask questions such as:
- Which object has the greatest mass? Why do you think so?
- Which object has the smallest mass? Why do you think so?
Pass around the different objects. Invite students to weigh them and place them in ascending order of mass (least to greatest) based on their estimates. Ask questions such as:
- Now that you have weighed the objects, would you like to change your estimates? Why?
- How can we verify that the objects are placed in ascending order of mass?
Students will likely suggest the use of a scale to determine the mass of objects. Ask questions such as:
- Does the ball with the largest diameter have the greatest mass?
- Does the ball with the smallest diameter have the smallest mass?
- Can you accurately determine the mass of an object just by looking at it? Justify your answer.
The pan balance will allow them to justify or modify their choice. Support students to recognize that the mass of objects is not always related to linear dimensions such as height, width and diameter.
Source: translated from Guide d’enseignement efficace des mathématiques, de la maternelle à la 3e année, Mesure, p. 130.
Activity 2: Well-Balanced Lunches
Goal
In this activity, students compare the total mass of their lunches, including the container (for example, lunch box, paper bag, plastic bag, cloth bag).
Materials
- each student's lunch (in its container)
- pan scales (one per team of four students)
- 8 x 11 sheet (one per student)
Instructions
Form teams. Have students weigh the lunches, including the boxes and bags of their team members, and estimate which has the greatest mass and which has the least mass. Have students individually record their estimates on a piece of paper. Using a pan balance, have each team determine the mass of each of their members' lunches and place them in descending order of mass. Have students compare their estimates with these results.
Group the teams together and ask them to bring the lunch with the least mass as well as the lunch with the greatest mass. Ask them to determine the lunch with the least mass, using a pan balance. Do the same to determine the lunch with the greatest mass.
Ask questions such as:
- Does the height of the container determine the mass of the lunch?
- Does the tallest and widest container have the greatest mass and the shortest and thinnest container have the least mass?
- What foods or beverages contribute the most to the mass of a lunch?
Source: translated from Guide d’enseignement efficace des mathématiques, de la maternelle à la 3e année, Mesure, p. 150.
Activity 3: Comparing Masses
Goal
In this activity, students measure the mass of objects in order to compare them to each other.
Materials
- various objects
- pan balance scales
- interlocking cubes, play money quarters, large paperclips, bolts, etc.
- worksheets
Instructions
Form teams.
Give each team a pan-balance scale, three different objects, enough non-standard units, and three sheets of paper with the names of the objects to be weighed.
Ask them to determine the mass of the three objects.
Support students that they need to place the object in one pan and the units of measurement in the other pan. The number of units needed to balance the scales is the measurement, for example, The mass of the pencil is 4 interlocking cubes
Ask students to write the mass of the three objects on the three sheets.
Ask them to place the three objects in ascending order according to their mass.
Ask them to specify the number of units of measurement between two objects.
Source: translated from L'@telier - Ressources pédagogiques en ligne (atelier.on.ca), p. 1.