I need help with this..

A young lady was working in a packing plant. While at her job she accidentally lost her ring in one of the cans. She did not know which can it had fallen into but she did know it must have fallen on one of the last nine cans she had packed. Without opening the cans & by using a balance scale only twice, what advice would you give the girl to help her find the ring as quickly as possible? Remember, the ring is in one of the NINE CANS & you can only use the balance scale TWICE.

TIP: you MUST use the balance scale to solve the problem

place 3 cans on each side of scale. If even, it's in one of the 3 cans left out. If so, take 2 of the 3 cans left out and put one on each side of scale. the heavier can or the one left out will be it. if the first weigh was uneven, take the 3 from the heavier side, put one on each side and weigh. the heavier can or the one left out will be it.