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Towering Success
Model Universe / Fascinating Food
Age range 7-14 with adult supervision
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- A box of cocktail sticks
- Cheese cubes or marshmallows or jelly sweets – or a combination
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- The idea is to build a stable structure – but which shapes are best? Here’s a quick rundown on the basics:
SQUARES AND CUBES
- Start with 4 cocktail sticks and 4 sweets. Poke the cocktail sticks into the sweets to make a square with a sweet at each corner.
- Poke another cocktail stick into the top of each sweet. Put a sweet on the top of each cocktail stick. Connect the sweets with cocktail sticks to make a cube. (A cube has a square on each side. It takes 8 sweets and 12 cocktail sticks.)
TRIANGLES AND PYRAMIDS
- Start with 3 sweets and 3 cocktail sticks. Poke the cocktail sticks into the sweets to make a triangle with a sweet at each point.
- Poke another cocktail stick into the top of each sweet. Bend those 3 cocktail sticks in toward the centre. Poke all 3 cocktail sticks into one sweet to make a 3-sided pyramid. (A 3-sided pyramid has a triangle on each side. It takes 4 sweets and 6 cocktail sticks.)
- For a 4-sided pyramid, you need a square on the bottom and triangles on all 4 sides. Build a square, and then poke a cocktail stick into the top of each corner. Bend all 4 cocktail sticks into the centre and connect them with one sweet, to make a 4-sided pyramid.
When you make a structure that uses both triangles and squares, you can make big structures that are less wiggly.
OK, so now you’ve got the idea, it’s time to set the rules and get creative.
- Set the rules: limit the number of sweets and cocktail sticks available per person and decide on the criteria for winning. It could be a) the tallest structure or b) the structure that can bear the most weight or even c) the one that most resembles a famous building. You can set a time limit if you want to be particularly strict.
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The inside story:
Even though the sweet structures are standing absolutely still, their parts are always pulling and pushing on each other. Structures remain standing because some parts are being pulled or stretched and other parts are being pushed or squashed. The parts that are being pulled are in tension. The parts that are being squashed are in compression.
Some materials, like bricks, don’t squash easily; they are strong in compression. Others, like steel cables or rubber bands, don't break when you stretch them; they are strong under tension. Still others like steel bars or wooden cocktail sticks are strong under both compression and tension.
What's the big deal about triangles? Well, squares collapse easily under compression. Four cocktail sticks joined in a square tend to collapse by giving way at their joints, their weakest points. A square can fold into a diamond – but it’s different for triangles. The only way to change the angles of the triangle is by shortening one of the sides. So to make the triangle collapse you would have to push hard enough to break one of the cocktail sticks.
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