Year 4 Properties of 2D and 3D shapes and symmetry worksheet

“Naming triangles by their sides” is free to print, with no account. It is the first sheet in the Year 4 maths unit “Properties of 2D and 3D shapes and symmetry”, for children aged 8 to 9, and takes about 21 minutes.

Print it on A4. The child's pages come first; the answers, and what each wrong answer tells you, are on the grown-up page that follows. Weeks 29 to 30 of the year, 10 sheets in the unit.

Free sample · answers on the last page

Naming triangles by their sides

Name: ____________ · Date: ____________
Year 4 · Maths · about 21 minutes
Answers are on the grown-up page

Today I can name a triangle by how many of its sides are equal, even when it is turned.

A Look back3 min

1.
A square has sides.
2.
A hexagon has vertices.
3.
A rectangle has right angles.

B Watch me, then you4 min

A triangle has sides of 4 cm, 7 cm and 4 cm. Which type of triangle is it?

Watch me

The sides are 4 cm, 7 cm and 4 cm.

Two sides are the same length, and one is different.

So it is an isosceles triangle.

Now you

1.
A triangle has sides of 3 cm, 5 cm and 6 cm. Which type of triangle is it?
equilateralisoscelesscalene

C Your turn7 min

Read the side lengths. Then circle the type of triangle.

A small triangular tent pitched on a grassy campsite beside a wooden picnic table, in sunshine

1.
A triangle has sides of 5 cm, 5 cm and 5 cm. Which type of triangle is it?
equilateralisoscelesscalene
2.
A triangle has sides of 8 cm, 3 cm and 8 cm. Which type of triangle is it?
equilateralisoscelesscalene
3.
A triangle has sides of 7 cm, 4 cm and 9 cm. Which type of triangle is it?
equilateralisoscelesscalene
4.
Mia turns a triangle upside down so it sits on its point. Its sides are 6 cm, 9 cm and 9 cm. Which type of triangle is it?
equilateralisoscelesscalene

Say it out loud: What changed from one triangle to the next, and what stayed the same?

D Spot the mistake3 min

Kit says: “A triangle with two equal sides is equilateral.”

1.
A triangle has sides of 6 cm, 6 cm and 4 cm. What type of triangle is it really?
equilateralisoscelesscalene

E Think deeper4 min

A triangular red pennant flag flying from a tall wooden pole against a blue sky

1.
Mia says a triangle with a right angle must be scalene. Is she right? Explain how you know.

How did it feel?

I can do it Nearly Not yet

For the grown-up

Naming triangles by their sides · 2 minutes to read

Answers, and what a wrong one tells you

A

1. 4

2. 6

3. 4

B

1. scalene

C

1. equilateral

2. isosceles If your child says equilateral, ask which sides match. The two 8 cm sides match, but the 3 cm side does not, so not all three match.

3. scalene If your child says isosceles, ask if any two sides are the same length. None are, so it is scalene.

4. isosceles If your child says scalene, read the lengths again. The two 9 cm sides match, even though the triangle is turned.

D

1. isosceles If your child says equilateral, look at the third side. It is 4 cm, not 6 cm, so the sides do not all match. Two equal sides means isosceles.

E

1. Look for: No, because an isosceles triangle can have a right angle, such as two equal sides meeting at a right angle.

Words to use

Say“Which sides match? Show me with your finger.”

Instead of“Just tell them the name of the triangle.”

After the sheet

Cut three triangles from an old cereal box. Pencil a dash on each equal side, then turn them upside down and name them again.

Tick what your child got right in StudyDen. Anything missed comes back in a later Look back box, so there's no need to redo the sheet.

The rest of this unit

9 more sheets come with a StudyDen plan, in teaching order:

Sorting triangles by sides and corners(with a plan)
Completing mirror patterns(with a plan)
Do Joined Shapes Match?(with a plan)
Folding for symmetry(with a plan)
Finding Lines of Symmetry(with a plan)
Flip the Dot(with a plan)
Reflecting Across the Mirror(with a plan)
Diagonal lines of symmetry(with a plan)
Looking for lines of symmetry(with a plan)

Every Year 4 maths worksheet

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