Understand the idea.
Count sides and corners
For a flat shape, a straight side runs between two corners. A corner is where two straight sides meet. Trace the boundary slowly so you can see where one side ends and the next begins.
Start at one corner and travel round once. Count each side and each corner only once, stopping when you return to the start. This avoids counting the first corner again as a new corner.
Describe a solid object
Describe solid objects using their surfaces. A cube has six flat square faces. A ball's surface is curved all around. These features help identify the object even if its size or colour changes.
A cylinder-shaped can has two flat round ends and one curved side. It can roll on its curved side, but it is not a ball. Look for flat surfaces as well as checking whether something rolls.
See the method in action.
Compare A and B
How do the triangle and square differ?
Worked solution
- 1
Count around triangle A once.
Its boundary has three straight parts meeting at three corners.
- 2
Count around square B once.
Its boundary has four straight parts meeting at four corners.
- 3
Describe the difference.
The triangle has three of each, while the square has four of each.
The triangle has 3 sides and 3 corners; the square has 4 of each.
A can and a ball
Both objects can roll. What feature helps tell them apart?
Worked solution
- 1
Check what rolling tells us.
Both objects roll, so rolling alone cannot tell them apart.
- 2
Look at the can's ends.
A cylinder-shaped can has flat round ends as well as a curved side.
- 3
Compare the ball's surface.
The ball is curved all around and has no flat ends, which distinguishes it from the can.
A can has flat ends; a ball is curved all around.
Try it yourself.
Check your understanding
Name one familiar flat shape with a curved boundary and no corners.
Show answer & reasoning
For example, a circle. An oval also fits.
A circle is one answer: its boundary is curved and has no corners. An oval also fits, so the description allows more than one shape.
Keep practising
6 worksheet questions
Read the questions online
- How many corners does pictured shape A have?
- How many corners does pictured shape C have?
- Does a ball have flat square faces?
- Name one solid object with flat faces.
- A solid has two flat round ends and one curved side. Name a familiar example.
- Describe a square without using its colour or size.
Read the worked solutions
- How many corners does pictured shape A have?
A is a triangle.
3. - How many corners does pictured shape C have?
Trace around its four corners.
4. - Does a ball have flat square faces?
A ball is curved all around.
No. - Name one solid object with flat faces.
Check that the object has a flat surface.
Answers vary, such as a cube-shaped block or box. - A solid has two flat round ends and one curved side. Name a familiar example.
Those are the features of a cylinder.
A can or cylinder. - Describe a square without using its colour or size.
Use the defining features, not appearance alone.
Four equal straight sides and four square corners.
Curriculum reference & lesson scope
Australian Curriculum v9 / SA Curriculum 2026
Year 1 making, sorting and describing familiar shapes and objects using spatial features.
Official curriculum source ↗