Communicating
Measures - Who’s Right? Let’s Talk it Through
Teacher Guide
Even though shape and number are involved, the key learning focus is communicating mathematical reasoning about area.
This task is explicitly about:
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Talking mathematically
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Explaining and justifying ideas
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Using representations to support explanation
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Listening to and responding to others’ thinking
Mathematical Resolution (for teacher reference):
An open cube has 5 faces, not 6. Each face has an area of 16 cm², giving a total surface area of 80 cm².
Progression Continua
Element
Communicating
f
The learner
Makes comparative statements or judgements.
g
The learner
Uses language of metric measurement to describe similarities and differences between attributes of objects.
h
The learner
Expresses measurements in appropriate metric units. Represents equivalent units of measurements in multiple ways.
i
The learner
Communicates and represents measurements using suitable and effective modes of presentation.
What children can typically do in this task
f
The learner
Makes a judgement about which student’s claim is correct or incorrect.
g
The learner
Uses terms such as face, surface area and square centimetres when discussing the cube.
h
The learner
Correctly expresses surface area in square centimetres and shows understanding of why 5 faces are counted.
i
The learner
Uses a diagram (net or 3-D sketch) and a clear explanation to justify the conclusion to others.
Teacher Scaffolding Questions Examples Prompts
To support discussion
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What does open change?
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Which face is missing?
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To deepen explanation
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How could you show that clearly in a diagram?
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How would you convince someone who disagrees?
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To challenge
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What if two faces were missing?
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How would the surface area change if the edge was doubled?
