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Year 4 · Patterns and algorithms · 14 min

Predicting and explaining patterns

Use a repeated change or a table to predict later terms and explain your prediction.

01 / LEARN

The idea, step by step

Make a table before predicting

Write the step number beside each value. This stops you mixing up the number of steps with the amount at a step. A display with 4 tiles at step 1 and 3 more tiles each new step has 7 at step 2 and 10 at step 3.

To reach step 5 from step 1, make four jumps, not five. List the intervening values or count the extra groups. Both methods should agree.

A growing tile display
StepTiles
14
27
310
413

Explain and check a prediction

Name the start, the change and the number of changes. I added 3 four times to 4 is clearer than I guessed 16. Check your method on a value already in the table.

A prediction assumes the stated rule continues. A table does not prove that a real quantity will grow forever. Read for limits such as a full box or a maximum number of seats.

A common trap

Step 6 means adding the increase six times to the step-1 value.

Instead: There are five jumps from step 1 to step 6. List the step numbers to count.

02 / WORKED EXAMPLES

See the thinking

Example 1

Count the jumps

A display has 4 tiles at step 1 and adds 3 each step. Find step 6.

  1. There are five jumps from step 1 to step 6.
  2. Five jumps add 5 × 3 = 15 tiles.
  3. 4 + 15 = 19. Check step 2: 4 + 3 = 7.
19 tiles.
Example 2

Check a practical limit

A box holds 40 counters. It starts with 5 and gains 7 each round. Is it exactly full after five rounds?

  1. Five rounds add 5 × 7 = 35 counters.
  2. 5 + 35 = 40 counters.
  3. 40 is the capacity, so the box is exactly full.
Yes, 40 counters.

Check your understanding

Step 1 has 6 tiles. Each new step adds 4. How many are at step 4?

Show answer

18 tiles

Three jumps add 12 tiles; 6 + 12 = 18.

03 / WORKSHEET

Your turn

6 questions · 13 marks · Work at your own pace.

Read the questions online
  1. A pattern starts with 8 at step 1 and adds 5 each step. Find step 5.
    2 marks
  2. Complete the table for a rule that doubles each time.
    2 marks
    StepValue
    13
    26
    3?
    4?
  3. Linked tables seat 4 people at step 1. Each extra table adds 2 seats. How many seats do 7 linked tables provide?
    2 marks
  4. A learner predicts that 21 follows 2, 6, 10, 14, 18. Check using the constant-addition rule.
    2 marks
  5. A tank starts with 10 litres. Each round adds 6 litres. It holds 40 litres. How many complete rounds fill it exactly?
    2 marks
  6. Make a constant-addition pattern with 9 at step 1 and 21 at step 4. State the rule and all four terms.
    3 marks
Read the worked solutions

Equivalent correct methods earn the corresponding marks. Include units where asked.

  1. A pattern starts with 8 at step 1 and adds 5 each step. Find step 5.
    2 marks

    There are four jumps.

    8 + 4 × 5 = 28.

    28
  2. Complete the table for a rule that doubles each time.
    2 marks
    StepValue
    13
    26
    3?
    4?

    3 × 2 = 6; 6 × 2 = 12; 12 × 2 = 24.

    Step 3: 12; step 4: 24
  3. Linked tables seat 4 people at step 1. Each extra table adds 2 seats. How many seats do 7 linked tables provide?
    2 marks

    Seven tables are six additions after the first.

    4 + 6 × 2 = 16.

    16 seats
  4. A learner predicts that 21 follows 2, 6, 10, 14, 18. Check using the constant-addition rule.
    2 marks

    Each jump adds 4.

    18 + 4 = 22.

    22, not 21.
  5. A tank starts with 10 litres. Each round adds 6 litres. It holds 40 litres. How many complete rounds fill it exactly?
    2 marks

    40 − 10 = 30 litres are needed.

    30 ÷ 6 = 5.

    5 rounds
  6. Make a constant-addition pattern with 9 at step 1 and 21 at step 4. State the rule and all four terms.
    3 marks

    There are three equal jumps.

    21 − 9 = 12; 12 ÷ 3 = 4.

    Add 4: 9, 13, 17, 21.
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Curriculum reference & lesson scope

Australian Curriculum v9 and SA Curriculum Mathematics 2026

Additive/multiplicative rules; steps/decisions; predicting and explaining patterns.

Official curriculum source ↗
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