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Make a piece of shortbread

By David, 13 January 2016 Activity

Safety: This activity involves an oven and electric beaters. Younger mathematicians should ask an adult for help.

You will need

Brown batter in a bowl

Mix the butter, sugar and essence with a fork.

  • 15 g butter, softened
  • 10 mL caster sugar
  • 0.3 mL vanilla extract
  • 31 mL plain flour
  • 8 mL rice flour
  • Extra butter to grease the baking tray
  • Extra flour for kneading
  • 2mL caster sugar to sprinkle on top

    A sieve with flour in it.

    Sift the dry ingredients.

  • Baking tray
  • Bowl
  • Set electric beaters
  • Sieve or sifter
  • Spoon
  • Measuring tools – a pharmacy will sell medicine cups and other tools for measuring small quantities.

What to do

A biscuit on a cooling rack.

Your completed shortbread.

  1. Preheat oven to 150°C and grease a baking tray.
  2. Use the electric beaters to beat the butter, sugar and vanilla together in a bowl, until they are pale and fluffy. If you are having difficulty using the beaters, try using a fork instead.
  3. Sift the flours and mix them with the mixture, using a spoon. This is your shortbread dough.
  4. Sprinkle some extra flour on the bench, and gently knead your shortbread dough until it is smooth.
  5. Roll the shortbread dough into a layer about 8 mm thick and put it on the baking tray. Sprinkle with some extra sugar.
  6. Put the shortbread in the oven for around 40 minutes or until it starts turning golden.

What’s happening?

It takes a lot of work to make one piece of shortbread with this recipe. However, if you want to make more than one, you don’t need to make them one at a time. If you work out how many pieces you want, you can multiply the quantity of each ingredient and make a recipe for exactly the right number of biscuits for you. That way, you’ll only need to measure and mix once.

When you’re multiplying this recipe, you’ll have to be a bit careful. You need to multiply each of the ingredients, but you don’t need to multiply all the other numbers in the recipe. If you were making 10 pieces of shortbread, you wouldn’t need 10 bowls, and you certainly wouldn’t want to bake them at 1500°C. However, you might need a second baking tray, and the shortbread might take a few minutes longer to cook.

Applications

Food companies are very interested in scaling up recipes. When they come up with a new recipe, they first make it in small batches in a laboratory. If the recipe is promising, then they will scale it up to be made in their factory. Whenever a new recipe is scaled up, food scientists have to run tests. Sometimes when a recipe is scaled up, some costs increase a lot, and a recipe that looked good in the lab is too expensive to produce in the factory.

More information

An example of scaling up a cake recipe
Why different things in a recipe scale at different rates (more advanced)

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