Number patterns: one term out
The rule is spotted ("it goes up by 4") and the answer is still wrong, because ten steps were added instead of nine. Repeating patterns have their own version: the position is divided by the length of the repeat and the remainder is read off wrongly.
What it looks like
A pattern goes 3, 7, 11, 15, … What is the 10th number?
- Each number is 4 more than the one before.
- From the 1st number to the 10th is 9 jumps: 9 × 4 = 36
- 10th number = 3 + 36 = 39
Why 43 is wrong: Ten jumps of 4 were added instead of nine: 3 + 40 = 43. The first number has no jump before it.
Why children do it
- Counting the jumps between terms gives one fewer than the number of terms, and the difference is easy to lose.
- The first term has no jump before it, but it still gets counted as one.
- For repeating patterns, a remainder of 0 means the last item in the group, not the first.
How to fix it at home
- Have your child write the term numbers above the pattern (1st, 2nd, 3rd…) and count the gaps, not the terms.
- Check the rule on a term you can see: does it give the 4th number correctly? Then trust it for the 10th.
- For repeating patterns, write the group once and number its positions. Divide, then use the remainder to read the position.
Questions parents ask
Are patterns tested with shapes too?
Yes. Figure patterns (sticks, dots, tiles) are the same skill: a starting amount plus a fixed jump each stage.
Should my child learn a formula?
A simple one helps: first term + (position − 1) × jump. The "− 1" is exactly where this habit lives.
How does Knowbotic catch it?
The one-term-out answer is a known trap on pattern questions, so a wrong answer is named as this habit and practised until fixed.
Where it shows up
Other careless mistakes
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