Every time you add one more tricycle, the wheel count always goes up by exactly 3. When one quantity changes and the other changes with it by a fixed rule, that's called a corresponding relationship.
A corresponding relationship is when one quantity changing means another quantity changes right along with it, as a matched pair. With 1 tricycle there are 3 wheels, with 2 there are 6, with 3 there are 9 — every time the number of tricycles goes up by one, the number of wheels always goes up by the same fixed amount. The key idea is that every x-value is matched with exactly one y-value.
Writing these matched-up numbers in a table makes the pattern easy to see, and plotting the table's values as dots turns them into a graph that traces a steady path. The straighter the dots line up, the simpler the hidden rule. You'll meet this same idea again in middle school under the name "function."
Move the slider to change the count and watch how the table and graph change together — try to spot the hidden rule yourself.
| x | y |
|---|