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Basic Shapes and Perimeter

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Foundational skills
Count vertices
\[ \text{Vertices} = 6 \]
Count the corners of a shape, including ones that point inwards.
Spot equal sides from marks
\[ \text{Which side} = p\text{?} \]
Use the little dashes to find which sides are equal.
Perimeter on a squared grid
\[ \text{P} = 14\text{ edges} \]
Count the square edges all the way round the outside.
Polygons and triangles
Name a polygon
\[ 7 \text{ sides} \to \text{heptagon} \]
Name a shape from its number of sides.
Regular or irregular?
\[ \text{Regular or irregular?} \]
Decide whether all the sides and all the angles are equal.
Triangles by their sides
\[ 5, 8, 5 \to \text{isosceles} \]
Name a triangle as equilateral, isosceles or scalene.
Triangles by their angles
\[ 30^\circ, 50^\circ, 100^\circ \]
Name a triangle as acute, right-angled or obtuse.
Quadrilaterals
Name a quadrilateral
\[ \text{Name it} \]
Use the marks on a diagram to name a quadrilateral.
Name it from its properties
\[ \text{1 pair of parallel sides} \]
Work out which quadrilateral fits a list of facts.
Count a property
\[ \text{Kite: parallel pairs?} \]
Recall the properties of each quadrilateral.
Symmetry
Lines of symmetry: triangles and quadrilaterals
\[ \text{Rectangle} \to 2 \]
Count the mirror lines of a triangle or quadrilateral.
Lines of symmetry: regular polygons
\[ \text{Hexagon} \to 6 \]
Count the mirror lines of a regular polygon.
Order of rotational symmetry
\[ \text{Order} = 2 \]
Count how many times a shape fits onto itself in one turn.
Perimeter: calculating
Add the labelled sides
\[ 4 + 7 + 3 + 6 + 5 \]
Add up every side, going all the way round.
Rectangle from two sides
\[ 2 \times (8 + 3) \]
Find the perimeter of a rectangle from its length and width.
Shapes with equal-side marks
\[ \text{Kite: } 5 + 5 + 9 + 9 \]
Fill in the equal sides first, then add them all.
Regular polygon from one side
\[ 8 \times 4.5 \]
Multiply the side length by the number of sides.
Mixed units
\[ 2\text{m} + 35\text{cm} \]
Change to the same unit before adding.
Perimeter: missing lengths and reversing
Missing length in a rectilinear shape
\[ x = 12 – 5 \]
Use opposite sides to find a missing length.
Perimeter of an L-shape
\[ \text{Fill in, then add} \]
Find the two missing sides, then add all six.
Perimeter of U, T and stepped shapes
\[ \text{Every side counts} \]
Find any missing sides, then add them all.
Side of a regular polygon from its perimeter
\[ 40 \div 5 = 8 \]
Divide the perimeter by the number of sides.
Side of a rectangle from its perimeter
\[ (30 – 2 \times 9) \div 2 \]
Take away the known sides, then halve.
Side of an isosceles triangle from its perimeter
\[ (25 – 7) \div 2 \]
Use the two equal sides to work backwards.
Extensions
Shapes made from identical rectangles
\[ \text{Outside edges only} \]
Find the perimeter of a shape built from identical rectangles.
Joined regular polygons
\[ \text{Don’t count the join} \]
Find the perimeter when two regular shapes share a side.
Equal perimeters
\[ 3 \times 12 = 4 \times x \]
Use one shape’s perimeter to find a side of another.
Perimeter as an expression
\[ 2(x + 3) + 2(2x) \]
Write and simplify an expression for the perimeter.
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