A balance comparison can challenge a size prediction

Put a large lightweight object beside a smaller comparison object and invite a prediction. A suitable balance provides evidence that appearance alone cannot supply, making the difference between looking larger and having greater mass discussable.

Compare items using the same balance arrangement. A visual judgement about size does not establish which object has greater mass.

Compare under the same arrangement

Check the empty balance. Compare two objects. Repeat with the same setup.

A larger-looking paper object need not have greater mass than a smaller object made differently.

Visual size alone does not establish mass.

What observation supports the comparison? Provide seated access and an observer role.

Resources

• Reflection Journal Template — Use the blank reflection space for observations; write the measurement units and setup separately.

Further reading

• ASIC Moneysmart — teaching lesson plans
• Australian Curriculum Version 9 — Mathematics

Read next

• Capacity: use the same measuring cup for both containers
• Read the picture-graph key before counting symbols
• Test reflection symmetry with corresponding points

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