From the editor - rhymes and mnemonics
I suppose I am quite lucky – I’ve got a reasonable memory and things tend to stick in my mind if there is a reason for remembering them (that doesn’t always apply when I’m in the supermarket but I absolutely refuse to ring my significant other while staring at the breakfast cereal and shouting, “Have we got any oats left?” so that the rest of the store can hear me). I used to have a problem with ‘necessary’ until someone advised me ‘Never Eat Curry, Eat Salmon Sandwiches and Remain Young’.
Our head of science was absolutely stunned when I started to tell him that ‘Henry Heinz Baked Beans Can Not Offer Full Nutrition So Munch Apples Since Prunes Sometimes Cause Awfully Painful Cramps’. He told me that he knows the properties of the elements of the periodic table and can visualise their positions/numbers because of their properties – there is the difference between a scientist and me!
What has caused me to write about mnemonics in this issue? Well, I was in a colleague’s lesson last week and heard a pupil half singing, half saying:
Hey diddle diddle the Median's the middle.
You add then divide for the Mean.
The Mode is the one you see the most.
And the Range is the difference between.
Feeling a bit like my head of science, I felt a bit uncomfortable to start with and started to question the pupil about mean, median, mode and found that he actually had a really good understanding of these measures of average but used the rhyme to remember which label to attach to each one. What could be wrong with that? It’s a bit like SOHCAHTOA isn’t it? Pupils can have a strong feeling for the ratios in similar right angle triangles and just need reminding that the one that involves opposite and hypotenuse is called Sine. That is completely different from pupils that tell me that what you do first is write down SOHCAHTOA, label the sides, cross out the one you don’t need etc…
So, on my drives to work this week I have been thinking about the memory aids that we use in the classroom which include:
Cherry pie’s delicious (c = πd)
Apple pies are too (a = πr²).
Twinkle, twinkle little star, circumf'rence is 2 π r
I didn’t really know you cared, area is π r squared.
A litre of water's
a pint and three quarters.
Two and a quarter pounds of jam
weigh about a kilogram.
But then I start to feel a bit uncomfortable again when I think about rhymes like:
It’s not for you to reason why,
Turn upside down and multiply!
Now – that takes things into another league for me. I feel I have moved away from helping pupils to remember labels for objects or definitions, and into the realm of memorising algorithms. Of course I want pupils to reason why. Why on earth do we turn upside down and multiply?
(If we think about the multiplicative relationships between 2 and 5,
2 x 5/2 = 5 so using inverse operations 5 ÷ 5/2 = 2 but we also know that 5 x 2/5 = 2 so ÷ 5/2 and x 2/5 are equivalent operations.)
So I also feel uncomfortable with the Welsh couple ‘Taf and Di’ (the self inverse functions Take From and Divide Into) and ‘All you need to do to add fractions is to remember the upside down picnic table’.
I’m sure you use similar aids in your classroom. Are they all ways of remembering labels or do they play another function. Why not tell us about them?