# MathsClass

A blog about teaching and learning in a maths classroom.

## Surface Area and Chocolate

Sunday, 16 August 2009 | 3 Comments

An excuse to use chocolate in a maths lesson…

Looking at Surface Area lends itself to practical activities, and two manageable activities involve chocolate.

First, find the surface area of a Smarties box.  This one is not my idea, but my colleagues at school use it – it may not even be theirs; searching for smarties box reveals a couple of lesson ideas.  I put together a simple worksheet as a scaffold where the students record the dimensions of the box, find the individual areas and then find the total – splitting it up allows me to find where they might have made a mistake.  Once they have a reasonable answer, they get to open the box and eat – which also lets them see the net of the box used for commercial packaging.  image source

We used to also use mini Toblerones which came in a triangular prism box.  However, the mini Toblerones don’t come in the box anymore, but soft packaging, so I adapted the lesson.  For a second activity, the students get a mini Toblerone and have to design a triangular prism box for it.  The worksheet is available below.  image source

Another way to include chocolate in the surface area topic is to discuss the new packaging of Cadbury’s block chocolates.  They recently changed the packaging to cardboard, but at the same time they reduced the weight of the products, whilst maintaining the size.  Read more on the Cadbury FAQ.  This video looks at this (thanks Scott for pointing me to it):

What could you do with this video in class?  At the moment, I will be using it as a discussion starter to consider how the people who designed the new packaging would have understood surface area and volume. Any better ideas?

Toblerone Design PDF, 200 KB

Posted in • Lesson IdeaSurface AreaMediaVideoPrintableWorksheetWhat can you do with this? | Short URL: http://mths.co/1610

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Tim on  21 August 09  at  09:23 PM #
The positive aspect of getting less chocolate in a block is that you eat less fat. You could create an activity to calculate the number of times you need to walk around the perimeter of the playground after eating a whole block of chocolate, to ensure that you don't increase the surface area and volume of your gut.
Derek Follett on  22 August 09  at  11:42 AM #
Last year I noticed that "half-gallon" ice cream containers said 1.75 quarts on them, now they are 1.5 quarts! Pretty soon they'll have us eating pints and thinking it's a half-gallon. What's really amazing is that all the ice cream manufacturers are in cahoots. This blogger also noticed [url=http://funfoodfight.blogspot.com/2008/07/ice-cream-melts-from-12-gallon-to-15.html]http://funfoodfight.blogspot.com/2008/07/ice-cream-melts-from-12-gallon-to-15.html[/url] Good to teach our students to be smart consumers.
Derek Follett on  22 August 09  at  11:48 AM #
How about this? Have students design a better box: create a box with at least 25% percent less cardstock but containing the same amount of candy. Once the project is complete ask: why might smarties prefer a less efficient package?

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Simon Job — eleventh year of teaching maths in a public high school in Western Sydney, Australia.
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