P5–P6 Growing patterns and tables
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PSLE 2023 — Rods and straws grid
A grid is built from rods and straws: the rods run one way and the straws run across them, so a grid m sections long and n sections wide needs a full line of straws down each of the m+1 divisions and a full line of rods across each of the n+1 divisions.
- (a) How many rods and straws altogether are used for a grid 3 rods long and 4 straws wide?
- (b) How many for a grid 4 long and 52 wide?
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The pattern behind it: Growing patterns and tables
Find the rule, so Figure 250 is no harder than Figure 4.
In this one. A row of k sections is bounded by k + 1 lines, not k — so each direction needs one line more than it has gaps: n + 1 lines of rods (m rods each) and m + 1 lines of straws (n straws each), never m × n twice.
How to spot it
A row of figures or a table of numbers is shown for the first few terms only, and the question asks for a term far further along, such as 'Figure 6' or 'Figure 250'.
Common mistake
Children extend the sequence one term at a time by drawing or counting. Finding the fixed step or relationship lets them jump straight to the term asked for.
Try one like it
Challenging PSLE 2025 — Two patterns common terms Pattern 1: 3, 7, 11, 15, ... Pattern 2: 7, 12, 17, 22, ... The number 7 is the first common term in both patterns. What is the sum…The 33 problem patterns
All 33 patterns, one to a page — the 19 behind Primary 5 and 6 word problems, and the skills the younger years are built on. The bar model, how to spot it in the question, and the mistake children make. A booklet you can print. Free.
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