C2.1 Identify when symbols are being used as variables, and describe how they are being used.

Activity 1: Rods


Using a set of relational rods, each team of two students:

  • discover all possible combinations of rods to obtain a given length;
  • assigns a value to each type of the coloured rod (for example, the white rod is worth 1, the red one is worth 2);
  • represents the combinations by number sentences (for example, 4 + 2 = 6);
  • replaces each number sentence with an equation that has a variable (or example, 1 + Δ = 6);
  • asks another team to solve the equations using the rods.

Source: translated from Guide d’enseignement efficace des mathématiques de la maternelle à la 3e année, Modélisation et algèbre, Fascicule 2, Situations d'égalité, p. 60.

Activity 2: Identify Constant and Variable Quantities


Read the first statement in list A to the students. Then read them the one in list B.

Ask students to determine which quantity is constant and which is variable.

List A List B
Number of legs on a chair Number of chairs in the house
Number of traffic lights in a city Number of colours on a traffic light
Number of sweaters in a wardrobe Number of sleeves on a sweater
Number of birds flying in the sky Number of legs of a bird
Number of handles in a house Number of handles on a door
Number of cars in the parking lot Number of tires on a car

Repeat the same exercise for the other statements in the lists.

Invite students to identify other constant and variable quantities in their daily lives.