Primary 5 Foundation maths · Geometry · About 12 minutes
Use rectangle and square properties excluding diagonals
Identify the relevant property before combining angle facts. Do not invent extra lines or equalities.
Start the interactive lesson →Open practice activity
What you will learn
- Use rectangle and square properties excluding diagonals
Models used: number sentences, stories, diagrams.
Before you start
A turn does not change the shape
Look for straight sides, corners and curved boundaries.
Look for straight sides, corners and curved boundaries.
Equal sides, parallel sides and complete angle sums supply different information. Use only what is given or follows from the named shape.
Follow the sides and corners. Turn the shape. Its sides are still the same length, and its corners have the same openings.
Turning a figure changes where it points. It keeps its side lengths and corner angles, so it is still the same shape.
Follow the sides and corners. The same figure, turned through 25 degrees. Use those features to recognise the shape, whichever way it is turned.
Turning a figure changes where it points. It keeps its side lengths and corner angles, so it is still the same shape.
Follow the sides and corners. Changing orientation preserves the shape.
What did the picture help us see?
Use those features to recognise the shape, whichever way it is turned.
Worked example: A new example, together
Which property must every square have?
Identify the relevant property before combining angle facts. Do not invent extra lines or equalities.
Four equal sides and four right angles
Use side and angle properties; diagonal properties are not required. Check the number of sides.
Use side and angle properties; diagonal properties are not required. Which property must every square have?
Four equal sides and four right angles
Check the number of sides.
Use side and angle properties; diagonal properties are not required. Check the angles at the corners.
Use side and angle properties; diagonal properties are not required. Four equal sides and four right angles.
Use side and angle properties; diagonal properties are not required. Check the result against the question we started with.
Measure every corner with a set square and compare the appropriate side lengths.
We found Four equal sides and four right angles. Four equal sides and four right angles
Use side and angle properties; diagonal properties are not required.
Common mistakes to discuss
- A square is not a rectangle. A square is a rectangle whose sides are all equal. Both have four right angles and opposite sides equal.
Check your understanding
- Use rectangle and square properties excluding diagonals
- connect shape properties with justified angle calculations
- check the answer against the original quantities and units
Explain your reasoning to an adult, then try a fresh question in the interactive lesson. A result from one attempt is not proof of lasting mastery.
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