Showing posts with label area. Show all posts
Showing posts with label area. Show all posts

Wednesday, 10 July 2013

Scale drawing and estate agents details

The perfect lesson (how to teach scale drawing)

scale drawing
As a young teacher I thought I had delivered the perfect lesson on scale drawing. I set the appropriate exercise and expected the pupils to enthusiastically tackle the tasks, applying their new found knowledge. What could go wrong? The folly of youth. Immediately a hand went up asking for help. 'What's the problem?' I enquired. 'You can't do this one' said the indignant pupil. The question involved working out the actual length a real car given the length of a toy car and the scale to which it was built. 'Why not?' I asked rather bemused. 'They haven't even told you what make of car it is. how can you possibly do it?' So much for the perfect lesson.

Wednesday, 3 July 2013

Estimation. School walls - don't tell Pink Floyd!

Estimation. How many bricks?

 Pink Floyd

This is  really simple lesson on estimation that makes the topic REAL!

It is easy to do and works, plus it allows you to escape the confines of the classroom.

I guess we have all heard the song 'The wall' by Pink Floyd. I enjoyed listening to it but was never quite sure about the lyrics. 

At this time of year I think most teachers would prefer to listen to Alice Cooper, you know the song 'Schools Out'. Just to remind you about Pink Floyd’s lyric

'We don't need no education
We don't need no thought control
All in all it’s just another brick in the wall'

Tuesday, 28 May 2013

Breakfast Maths or the cereal that never ends

A cereal lesson 

Here is an idea that will get you plaudits from those that like to see Maths in a context or ‘real life’ Maths. It will give a different pace to your lessons and engage those who prefer a kinesthetic learning style or experience. Yet again what you do depends upon your imagination and perhaps appetite.


Eat lots of cereal. Ban toast for breakfast and force, if you have to, your family to eat packets and packets of cereal. Keep the boxes. No recycling. You have to supervise the opening of the boxes as you want them to be in as good a condition as possible.

The Lesson

Organise the class into groups around tables, 4 to a table seems to work. As the proud owner of numerous cereal packets distribute one or more to each group. Ask the class what they could find out about the boxes, give them a minute or two to jot down some ideas then collect one from each table and record them on the board. It is now up you how you progress. Sometimes I have collected the ideas from the class, recorded them on the board, and then discussed what we have to find. Alternatively I have collected the ideas but also handed out a worksheet to some classes listing what needs to be found or what tasks they have to do. Here are some suggestions of what they have to do and record as a group.

Find the height, width and length of the box.

Find the volume of the box.

Draw a net of the box to scale.

Make an isometric drawing of the box.

Find the surface area.

How much does the it cost per gram? per 100g?

How many boxes could fill the classroom?

What is the ratio of sugar to salt? Does it fit in with Government guidelines?

If it takes 10 days to eat a box how much salt would I consume in a year?

Further ideas

There are always new and exciting ways to tackle topics. Buy this books and you will be generating  even more ideas for yourself 100+ Ideas for Teaching Mathematics (Continuum One Hundreds) .
As one reviewer says  'I was looking for a book which would inspire me when planning sessions for teaching mathematics. I browsed a number of books but this one was definitely the best as far as I could see on-line. When it arrived it was even better than I expected. I would certainly recommend this book to anyone who teaches maths! '

Extension ideas

Alternatively you could work on the suggestions gathered from the class. The outcome could be  report produced by each group or answers in their books from  prepared worksheet by you.

You could provide them with boxes of the same product but in different sizes which is the best value? I am sure you can think of other ideas. Happy eating. (By the way you have noticed a picture of porridge, I don't eat any other cereal these days, can't think why.)

Friday, 17 May 2013

Area, equations and that frog again

Those of you who read my post about how to use a frog to solve equations might want to use this before that lesson. It can also be used independently before starting to find the areas of complex shapes. It is deceptively simple, but powerful.


All you need to do I draw two lines and on one put its length, say 10cm, and on the other x cm and 8cm. Explain that the two lines are the same length. Two frogs have a jumping competition, they agree to jump over the same course of 10 cm. The first jumps the full 10 cm. Fred the frog jumps but only a distance of  x cm but then covers the rest of the course, which is 8 cm. How far is x cm?

As you know this is really x + 8 = 10. Depending on the level of pupils you can continue with further examples, make the link to algebra or move on.


The next step (or jump if you are a frog) is to draw similar lines  such as one which is 10 cm and the other which is x cm, x cm and 3 cm or whatever appeals to you. Again you can use the story of the two frogs one jumping the full 10 cm the other Fred covering x, cm then x cm then 3 cm. Emphasise that both x cm are the exactly  the same distance. Then ask how far is x cm?

Of course the pupils are solving 2x + 3 = 10. You can judge how far to take this idea it really does depend on the class or pupil. Use in its simplest form before doing complex shapes as pupils often fail to grasp how to find a missing dimension.


If you are wondering about previous mentions of Fred the frog see my previous post ‘solving equations with a frog’.


If anyone has used the ideas that I have given you over these last few blogs how did it go? Were they successful? How did you improve them? (I'm sure you can). Please leave a comment.