11 Plus Exams Forum

Does anyone know any good websites or books to explain ratios? Daughter in Yr 5 due to take Kent test in Sept and often struggles with these sort of questions.

have you tried the BBC ?

They have some excellent games and ideas,

try googling "ratio" you should be able to find some interesting sites.

Also try scaling recipes up and down (and cook themm if you are feeling brave)

Why not go to a big Waterstones or WH Smiths and look through the KS2 maths books with her, and get her to choose one she likes the look of, with particular reference to the ratio section. Also, see if she has covered it at school already, and look at whatever teaching methods they used then.

Also, follow the links in some the other maths threads and you will find some good websites for KS 2 stuff

Good luck

I would also share out sweets (or similar) is n the ratio 2:3 ie I give Mary 2 sweets for every 3 sweets I give John - then compare amounts after each 'sharing'.

2:3 = 4:6 = 6:9 are all equivalent ratios

Then look at 2:3 is the same as sharing something into 2/5 and 3/5 - this is quite a big jump.

Make up squash - 1:4 is common but you may be able to find others in the shop. If I pour out 10 ml of concentrated squash how much water do I need to add? later move on to - if I've made up 200ml of diluted squash how much water did I use?

Hi Kentish Maid

I agree that it is necessary to show a students the foundations of ratio. However, under test conditions they need a good mathematical method & technique.

For working out the distribution of an amount the student quite simply needs to work out the "value of one unit".

The simplest ratio is the 2:1 ratio.

There are 2 + 1 = 3 units

So if a value of say 24 needs to be distributed 2:1

Divide 24 by 3 = 8

Therefore 2 units is 2 x 8 = 16
and 1 unit is 1 x 8 = 8

The student can check the answer 16 + 8 = 24

24 is a good value to use as you can apply

2:1, 3:1, 5:1, 7:1 and 11:1 ratios as well as the 3:2:1 ratio

When looking for books, look at those that contain a good explanation and example with some exercises, always evaluate whether the student understands and completes exercise correctly, then extend to more complex questions.

Regards

Mike

Mike -

It is really important that practical work and plenty of it comes first - ratio is at the heart of so much secondary mathematics that the 'formal' stuff must NOT be rushed -

Children will not understand how powerful ratio is if they have not tried out some of these activities I suggest.