Shapes within shapes | Maths | Quizalize & Oak National Academy

Starter quiz

25% of 2640 is ______.

'660' ✓
20 as a percentage of 50 is ______%

'40' ✓
The area of a square with edge lengths of 1.4 cm is ______ cm².

'1.96' ✓
The area of a circle with a diameter of 30 m is ______ $\pi$ m².

'225' ✓
Here are the first seven triangular numbers: 1, 3, 6, 10, 15, 21, 28. The next triangular number is ______.

'36' ✓
The numbers 1, 4, 9, 16, 25, 36, 49, ... are called the ______ numbers.

'square' ✓

A shape has a total area of 50 cm². Part of the shape is shaded. An area of 24 cm² is left unshaded. ______% of the shape is shaded.

'52' ✓
A shape has a total area of 45 cm². Part of the shape is shaded. An area of 27 cm² is left unshaded. ______% of the shape is shaded.

'40' ✓
Which descriptors of this shape are correct?

This is a compound shape. ✓

This is a congruent shape.

This is a rectilinear shape. ✓

75% is shaded

80% is shaded ✓
The percentage of the shape which is shaded is ______%.

'75' ✓
Which calculation is correct to find the percentage of the rectilinear compound shape which is shaded?

$\frac{10\times5}{9\times9+7\times12}\times100$

$\frac{9\times9+7\times12-10\times5}{9\times9+7\times12}\times100$ ✓

$\frac{10\times5}{9\times9+7\times12-10\times5}\times100$

$\frac{9\times9+7\times12-10\times5}{10\times5}\times100$
This shape is made from a circle and the removal of two congruent circles. The percentage shaded in this shape is ______%.

'50' ✓

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You can express a number as a fraction of another and therefore as a percentage.
If you have two areas, you can express one as a percentage of another.
This can involve calculating with a variety of shapes.
A calculator can be very useful here.

Using the incorrect value for finding the percentage, for instance, the area of the unshaded when it asks for the shaded region.

Encourage pupils to underline/highlight whether they are finding the percentage of the shaded or unshaded region.

Area - The area is the size of the surface and states the number of unit squares needed to completely cover that surface.