What is an algorithm?

Understanding algorithms as step-by-step instructions to solve a problem, like a recipe or directions

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Try each question. If you're stuck, leave it and come back. The answer key is on the last page.

1
What is an algorithm? A) A step-by-step set of instructions to solve a problem B) A type of computer C) A computer game D) A picture on a screen
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2
True or false? A recipe for making a cake is an example of an algorithm. A) True B) False
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3
Put the steps for brushing your teeth in the correct order. Put these in order: Pick up toothbrush, Put toothpaste on brush, Brush your teeth, Rinse your mouth
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4
True or false? A good algorithm should be clear and not confusing. A) True B) False
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5
Which of these is NOT an example of an algorithm? A) A pile of random colourful crayons B) Instructions to make a sandwich C) Directions to the park D) Steps for tying shoelaces
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6
Put these steps for making toast in the correct order. Put these in order: Get a slice of bread, Put bread in toaster, Switch the toaster on, Wait for toast to pop up, Spread butter on toast
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7
Complete the sentence about algorithms. An algorithm is a set of ___ instructions.
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8
Match each example to whether it is an algorithm or not. Match each item on the left to one on the right. Left: Recipe for pancakes, Steps to log into a computer, A photo of a cat, A box of mixed-up bricks Right: Algorithm, Algorithm, Not an algorithm, Not an algorithm
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9
Put the steps for crossing the road safely in the correct order. Put these in order: Stop at the kerb, Look both ways, Listen for cars, Cross when it is safe
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10
Which of these is NOT a good algorithm? A) Walk, then turn, then maybe stop or maybe carry on, you decide B) Walk forward 3 steps, turn right, walk forward 2 steps C) Forward 5, right turn, forward 5 D) Step, step, step, stop
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Answer key

What is an algorithm? · for parents and teachers

1
A step-by-step set of instructions to solve a problem
An algorithm is a clear, step-by-step set of instructions for solving a problem or completing a task.
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True
True. A recipe gives step-by-step instructions, just like an algorithm.
3
Pick up toothbrush, Put toothpaste on brush, Brush your teeth, Rinse your mouth
Algorithms need to be in the correct order. You must pick up the brush before adding toothpaste, then brush, then rinse.
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True
True. Algorithms must be unambiguous (clear) so they can be followed correctly every time.
5
A pile of random colourful crayons
A pile of crayons is not a set of instructions. The other options are all step-by-step ways to do something.
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Get a slice of bread, Put bread in toaster, Switch the toaster on, Wait for toast to pop up, Spread butter on toast
The order of steps in an algorithm is very important. Each step must happen in the right place.
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step-by-step
Algorithms are step-by-step instructions that must be followed in order.
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Recipe for pancakes → Algorithm; Steps to log into a computer → Algorithm; A photo of a cat → Not an algorithm; A box of mixed-up bricks → Not an algorithm
Algorithms are ordered sets of instructions. Photos and random objects are not algorithms.
9
Stop at the kerb, Look both ways, Listen for cars, Cross when it is safe
This safety algorithm helps us cross roads safely: stop, look, listen, then cross.
10
Walk, then turn, then maybe stop or maybe carry on, you decide
A good algorithm has clear, exact steps. 'Maybe' or 'you decide' is not clear enough for a computer.