Definition
Shrinking pattern
A shrinking pattern has terms that get smaller according to a rule.
What it means
Read the pattern from one term to the next. Something becomes less each time, but “less” is not the whole rule. Say exactly how it shrinks—such as subtract 3, halve the amount, or remove two tiles—and check that rule at every step.
Remember it
Watch what leaves at each step, then name the exact rule that makes it leave.
Example
In 18, 15, 12, 9, each term is 3 less than the term before it. The shrinking rule is “subtract 3.” Use the rule once more to find the next term: 9 − 3 = 6.
Watch for
A list getting smaller is not enough by itself: the stated rule must explain every transition in the range being discussed.
Common mix-up
Shrinking does not always mean subtracting the same number. A pattern can shrink by division or by consistently removing parts.
Exact meaning
A shrinking pattern is an ordered pattern whose terms decrease in numerical value, size, or number of parts according to a rule that explains every step in the stated range.