Add-the-Previous-Two Patterns (Grades 5–6)
Some sequences build each term by adding the two before it — the famous Fibonacci pattern: 1, 1, 2, 3, 5, 8, 13.
Understanding add-the-previous-two patterns
There's no single common difference or ratio; instead, the rule looks back two steps. To extend it, add the last two terms.
Seeing it in action
Worked example
Continue: 1, 1, 2, 3, 5, __.
Add the last two: 3 + 5 = 8.
Each new term uses the two before it.
A common mistake, and the fix
Adding a fixed step instead of the two terms before.
After 1, 1, 2, 3, 5, the last jump was 2, so “add 2 again” gives 7, but each term is the sum of the two before it, so the next is 3 + 5 = 8.
Try a few
2, 3, 5, 8, 13, __
13 + 8.
1, 4, 5, 9, __
9 + 5.
0, 1, 1, 2, 3, __
Try it in Numeris.
A short lesson, then practice with feedback on every answer.
Put the reasoning on paper.
Try six fraction, angle, perimeter and area questions with explained answers, for grades 4–6.
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