KS3 Maths at Marwell
Porcupine ratios
Porcupine ratios
This activity uses equivalent ratios and ratios in their lowest terms.
The students will work through the sheet thinking about different ratios of fruit and
vegetables for porcupines to be fed.
This activity can be used either as a reminder/starter for a more able group or as a
developmental activity for a less confident group.
Wit h man y t h an k s t o Jo K er sh aw and De n efi eld Sc h ool f o r t hei r e xt en siv e
con t ri b ut i on t o de vel opin g t hi s r e so u rc e
Curriculum Links
MATHEMATICS
Ratio, proportion and rates of change
 use ratio notation, including reduction to simplest form
 divide a given quantity into two parts in a given part:part or part:whole ratio;
express the division of a quantity into two parts as a ratio
 understand that a multiplicative relationship between two quantities can be
expressed as a ratio or a fraction
Porcupine ratios
Every evening Karina the zookeeper
feeds the porcupines apple, carrot,
cabbage and potato.
For each porcupine she chooses:
Apple
Carrot
Cabbage
Potato
300g
140g
140g
90g
We say:
“the ratio of apple : carrot : cabbage : potato is 300 : 140 : 140 : 90”
In each of the boxes below:
a) write the food mix as a ratio of apple : carrot : cabbage : potato
b) decide which are in the same ratio as the food mix above (what we call
equivalent ratios) and explain your thinking
Apple
Carrot
Cabbage
Potato
30g
14g
14g
9g
Apple
Carrot
Cabbage
Potato
90g
52g
52g
90g
Apple
Carrot
Cabbage
Potato
a)
a)
a)
b)
b)
b)
Apple
Carrot
Cabbage
Potato
6g
2g
2g
1g
Apple
Carrot
Cabbage
Potato
52g
90g
52g
27g
Apple
Carrot
Cabbage
Potato
a)
a)
a)
b)
b)
b)
600g
280g
280g
180g
3kg
1.4kg
1.4kg
0.9kg
In addition to the apple, carrot, cabbage and potato, Karina chooses 2 extra
vegetables each day.
Last week Karina chose the following vegetables:
Ratio in its
lowest terms
Monday
Swede 150g
Broccoli 150g
Tuesday
Broccoli 150g
Wednesday
Parsnips 100g
Sweet potato
70g
Swede 150g
Thursday
Broccoli 150g
Peppers 65g
Friday
Swede 150g
Cauliflower
100g
Match the ratios below to the food mixes in the table. Watch out – there is
one spare ratio that doesn’t have a match!
30:17
15:7
3:2
2:3
30:13
1:1
Saturday and Sunday’s choices are shown below. Write the ratios in their
lowest terms.
Saturday
Peppers 65g
Sunday
Cauliflower
100g
Sweet potato
70g
Swede 150g
Explain what an equivalent ratio is, and how to write a ratio in its
lowest terms: