Anchor Chart · Grade 7 · 7.RP.A.2.b
Roots of Reason
rootsofreason.org
how much for one?
The Constant of Proportionality
Apples cost $2.50 per pound. Find k = 2.50 in all five representations.
1Words
Apples cost
$2.50
for every 1 pound.
"For every 1" gives k directly.
2Table
| lb | 2 | 4 | 6 |
| $ | 5 | 10 | 15 |
| $ ÷ lb | 2.50 | 2.50 | 2.50 |
No row shows 1 pound. k = $ ÷ lb on any row.
3Equation
k is the number multiplying x. Nothing is added.
4Graph
k is the y-value at x = 1.
5Diagram
The value paired with 1 is k.
k is the amount
per one.
Once you know k, multiply by x to find any y.