Sequential Design – MYP Year 5 Extended Algebra Investigation
MYP Year 5 Extended sequential design tasks: how to investigate, generalise, and justify growing patterns. Aligned to Criterion B investigation structure.
What Sequential Design Means in MYP Context
Sequential Design tasks ask students to analyse a visual or structural pattern that grows according to a sequence rule, then use algebra to describe that growth. These tasks are almost always framed as Criterion B investigations, and often connect to Criterion D when the pattern represents a real or designed object.
The Shape of a Criterion B Investigation
MYP Criterion B (Investigating Patterns) has four strands. In a sequential design task, students are expected to:
- Select and apply a strategy to identify the pattern (typically: draw the next stage, tabulate values, look for the rule)
- Describe patterns — in both words and algebra
- Verify that their general rule works for cases they have not yet drawn
- Justify why the rule is correct — not just that it gives the right numbers, but why it must
What Students Actually Do
A typical sequential design task might show a sequence of shapes — for example, a growing arrangement of squares or hexagons — and ask students to find the number of tiles, edges, or intersections at stage n. Students build a table, identify the pattern type (linear, quadratic, or other), write the general rule, and test it.
Moving from Observation to Algebra
The critical transition in these tasks is moving from noticing a pattern to writing an explicit algebraic formula and explaining why it works. Students who only describe the pattern verbally cannot access the top Criterion B descriptors.
Common Weaknesses in Student Responses
- Providing a correct formula without any verification step
- Verifying only for n = 1 or n = 2 (which were given) rather than for an unseen stage
- Describing the pattern recursively without providing an explicit formula
- Not justifying why the formula must work — only that it does for the tested cases
How to Structure a Strong Response
A well-structured sequential design response includes: a labelled table of values, a clearly stated general rule in algebraic form, at least one verification using an untested stage, and a written justification which may refer to the physical structure of the design to explain where each term in the formula comes from.