Idea 18of 21Builds onJump ahead with the rule
Make a pattern, then prove it
How do you prove a number is, or is not, in a pattern?
Today you'll discover
- how a rule creates a pattern
- how to test a far number
- how to explain your answer
Think firstRule: start at 4, add 3
4, 7, 10, 13 … Will 40 ever be in this pattern?
Decide first, then press Next. Use the rule as your reason.
A row of boxes, 4, 7, 10, 13, made by the rule start at 4 and add 3, with jumps marked plus 3; the row extends to 16, 19, 22, and the terms are drawn as dots climbing to the right.
See the whole ideathe big idea and the key word, in one place
The big idea
A pattern rule makes the pattern, and it can prove whether a number belongs.
Make your ownStart at 2, add 5: 2, 7, 12, 17 … Does 102 belong? 102 − 2 = 100, which is 20 jumps of 5, so yes.
Easy to get wrong'It looks right' is not a reason. A justification uses the rule: the start, the change, and how many jumps.
Key word
- justify
- to explain why something is true, using the rule
Ready to use it?
- Make a pattern from a rule you choose.
- Prove whether a number belongs to a pattern.