Station A: Variable Sort Cards

Learning intention: I can classify numerical variables as discrete or continuous and explain how the data was collected.

Success criteria: I can identify counted data, identify measured data, use words such as whole numbers, decimals, units and precision, and justify my choice using the context.

Instructions: Cut out the cards. Read each context, then write discrete or continuous in the classification box. Use the cards to complete the reasoning table.

Word bank: count, measured, whole numbers, decimals, units, time, length, mass, temperature, precision.

Reasoning Table

Record the classification and give evidence from the card. Use a sentence starter if helpful: “I chose ______ because the variable is ______.”

Discussion prompts

1. Which cards are clearly counted? What makes them discrete?

2. Which cards are measured? What units or measuring tools give you evidence?

3. Can a continuous variable be recorded as a whole number? Explain using Card 19.

4. Why does the display on Card 20 not automatically make the original variable continuous?

5. Compare the number of laps with the distance travelled. How are the two variables different?

Support and challenge

Reading support: Read the cards aloud with a partner. Highlight words such as number, height, time, mass and temperature. Use the reminder: discrete means counted; continuous means measured.

For an extra challenge: Choose one continuous card and describe how its answer would change if it were measured to the nearest whole unit, nearest tenth, or nearest hundredth.

Teacher Answer Key

Discrete: Cards 1–8. These variables are counted and meaningful values are whole numbers.

Continuous: Cards 9–16. These variables are measured and can take decimal values, depending on the precision of the measuring tool.

Tricky cards:

Card 17: Discrete. Laps are counted; a completed lap is a whole item.

Card 18: Continuous. The amount of milk is measured, even though the recording has limited precision.

Card 19: Continuous. Temperature is measured. Recording to the nearest whole degree changes the precision, not the type of variable.

Card 20: Discrete. Steps are counted. A tracker may show an estimate or decimal display, but the number of steps is still a count.

Key vocabulary: Discrete data is counted. Continuous data is measured and can take any value within a range. The units and method of collection provide evidence.

Teacher check: Accept a classification when the justification is linked to the context, not merely to whether the recorded answer happens to contain a decimal.