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Generating a pattern from a rule

Generate a number or shape pattern that follows a given rule; identify apparent features of the pattern not explicit in the rule and explain informally why they occur

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What a learner can do afterwards

  • Given 'start at 1, add 3', generate terms and notice they alternate odd/even
  • Given a shape pattern, predict the next three terms and describe the rule
  • Explain why starting at 2 and adding 4 always gives even numbers

1 · Read

A pattern rule tells you two things: where to start, and what to do every time. If the rule is 'start at 1, add 3,' you begin at 1, then add 3 again and again: 1, 4, 7, 10, 13. The step does not have to be adding. 'Start at 3, multiply by 2' gives 3, 6, 12, 24, 48.

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Look closely: 1 is odd, 4 is even, 7 is odd, 10 is even, 13 is odd. Every other number flips between odd and even.
Try it together

Zara makes a shape pattern: circle, square, circle, square, circle. The rule is 'circle, then square, repeat.' The next three shapes are square, circle, square. Some patterns repeat a longer group, like circle, circle, square. Find the group that keeps coming back, then carry it on.

circlesquarecirclesquarecircle???

Patterns often hide a surprise the rule never mentions. In 1, 4, 7, 10, 13 the numbers flip odd, even, odd, even. That happens because the step, 3, is odd, and adding an odd number always swaps odd for even. When the step is even the flip never happens: start at 2 and add 4 and every number stays even, because even plus even is even.

A rule sets the start and the step, and once you build the pattern, watch for surprises hiding inside it, like numbers that keep flipping between odd and even.

2 · Watch

Take it off screen

Print a worksheetA4 with an answer key page for grown-ups. No screen, no internet.

Where it sits

Then practise

8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.

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Generating a pattern from a rule · Mathematics, ages 9 to 10 · LightMySky