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Find the Missing Piece

A blank box in the middle of a pattern is a puzzle. Use the rule before and after the gap to find what belongs there.

Class 3 to 5beginner15 min3 lessons
By the end you will be able to
  • Find a missing shape in an AB pattern
  • Use both sides of a gap to check your answer
  • Fix a pattern when two boxes are blank

Finish first

Pattern or Random?
Topic contents

Lesson 1 of 3

Look around the gap

Imagine red-blue-red-?-red. The blank sits in the middle. Look left: red comes before the gap. Look right: red comes after the gap.

In AB, red might be A and blue might be B. Before the gap is red, so B should sit in the blank, then red continues the pattern.

Always check both neighbors of the gap. One side alone can trick you if the pattern is longer than you thought.

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Lesson 2 of 3

Growing gaps

A growing pattern might show 1, 2, ?, 4. The rule adds one each step, so three belongs in the blank.

Write the numbers under the pictures even when one picture is missing. Numbers make the growth rule easier to see.

If two boxes are blank, solve the closest one first. Then use your new clue on the second blank.

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Lesson 3 of 3

Double-check

After you fill a gap, read the whole pattern from the start. Your fix should make every step follow the same rule.

Swap answers with a partner. If you disagree, point to the repeat unit together until you agree.

Next you will hunt for patterns that already exist in nature around you.

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Practice

Work these out yourself

No answer key here on purpose: these are the questions worth thinking through before you move on. Open one and work it out.

0/3 attempted

Assessment

Check your understanding

Answer each question, then read the explanation. That is where the learning is.

0/4
  1. Question 1: Red-blue-red-?-red. What most likely fills the blank?
    Question 1 / 4

    Red-blue-red-?-red. What most likely fills the blank?

    Select an option first
  2. Question 2: Why check both sides of a gap?
    Question 2 / 4

    Why check both sides of a gap?

    Select an option first
  3. Question 3: In 1, 2, ?, 4, the missing number is what?
    Question 3 / 4

    In 1, 2, ?, 4, the missing number is what?

    Select an option first
  4. Question 4: If two blanks sit in one row, solve first the blank that is what?
    Question 4 / 4

    If two blanks sit in one row, solve first the blank that is what?

    Select an option first
4 of 4 questions left.

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