Notes and Guidance
Children apply their knowledge of measuring and finding perimeter to find the unknown side lengths. They find the perimeter of shapes with and without grids. When calculating perimeter of shapes, encourage children to mark off the sides as they add them up to prevent repetition of counting/omission of sides.
What can you tell me about the sides of a square/rectangle?
How does this help you work out this question?
How can you use the labelled sides to find the length of the unknown sides?
What strategies can you use to calculate the total perimeter?
What does regular mean?
Why are rectangles irregular?