Year 4 Perimeter worksheet

“Regular or Irregular Shapes” is free to print, with no account. It is the first sheet in the Year 4 maths unit “Perimeter”, for children aged 8 to 9, and takes about 20 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 8 to 9 of the year, 10 sheets in the unit.

Free sample · answers on the last page

Regular or Irregular Shapes

Name: ____________ · Date: ____________
Year 4 · Maths · about 20 minutes
Answers are on the grown-up page

Today I can tell whether a shape is a regular polygon by checking equal sides and equal angles.

A Look back3 min

1.
4 rows of 5 counters. How many counters? 4 × 5 =
2.
6 tens and 3 ones make
3.
407 470. Write the sign that goes in the box.

B Watch me, then you4 min

Is a square a regular polygon? Check both rules, then decide.

Watch me

All four sides are the same length.

All four corners are right angles, so they measure the same.

Both rules hold, so a square is a regular polygon.

Now you

1.
A rectangle is 8 cm long and 3 cm wide. Is it regular or irregular? Circle one.
RegularIrregular

C Your turn6 min

Check both rules for each shape. Circle regular or irregular.

1.
Each side is 4 cm. Each corner is a right angle. Regular or irregular? Circle one.
RegularIrregular
2.
Two sides are 9 cm and two sides are 4 cm. Each corner is a right angle. Regular or irregular? Circle one.
RegularIrregular
3.
Each side is 2 cm, and every corner measures the same. Regular or irregular? Circle one.
RegularIrregular
4.
Each side is 5 cm, and every corner measures the same. Regular or irregular? Circle one.
RegularIrregular

Say it out loud: Which rule did each irregular shape break? Which rule did the regular shapes pass?

D Spot the mistake3 min

Mia says: “This rhombus has four equal sides, so it must be a regular polygon.”

1.
Is Mia right? Circle one answer.
Yes, all four sides are equalNo, the corners do not match in sizeNo, the sides are different lengths

E Think deeper4 min

A regular octagon has 8 equal sides and 8 equal corners.

1.
Draw a shape with 8 equal sides that is not a regular octagon. Explain how you know it is not regular.

How did it feel?

I can do it Nearly Not yet

For the grown-up

Regular or Irregular Shapes · 2 minutes to read

Answers, and what a wrong one tells you

A

1. 20

2. 63

3. <

B

1. Irregular If your child says regular, ask about the sides. 8 cm and 3 cm differ, so the first rule fails. Both rules must hold.

C

1. Regular

2. Irregular If your child says regular, compare the long and short sides. 9 cm and 4 cm differ, so the first rule fails even though the corners match.

3. Regular If your child says irregular, test each rule on its own. All six sides match and all six corners match, so both rules hold.

4. Regular If your child is unsure, count the sides and check that the corners match. Then say which rule the shape passes.

D

1. No, the corners do not match in size If your child circles yes, ask about the second rule. A regular polygon needs matching corners too. Point to the narrow corners and the broad corners.

E

1. Look for: A shape with 8 equal sides but corners that differ in size, with an explanation that the corners differ. If your child draws a regular octagon, ask: do all its corners measure the same? Then push one corner sharper and check again.

Words to use

Say“Check both rules: are all the sides equal, and do all the corners measure the same?”

Instead of“Say that looks regular and move on.”

After the sheet

Find three flat objects at home, like a tile, a book cover or a box lid. Check the sides with a ruler and the corners with a folded sheet of paper.

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:

Walking all the way round(with a plan)
Different Shapes, Same Perimeter(with a plan)
Counting around shapes(with a plan)
Adding the sides(with a plan)
Doubling the sides(with a plan)
Finding the Missing Side(with a plan)
Perimeter with multiplying(with a plan)
Sides from the perimeter(with a plan)
Perimeter puzzles(with a plan)

Every Year 4 maths worksheet

The worksheets plan opens a printable sheet for every lesson in Years 1 to 6, each with its answers on a separate page for you. It costs £6.99 a month or £59 a year for the whole family, with no free trial.

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