How Do Spring Scales Work?

Did you know that the spring scale got its name because it uses actual springs to measure mass/weight?

Okay, I'm not the most mechanically inclined person. Uh um...actually even the thought of visiting the furniture aisles at IKEA makes me shudder. But, I am interested in learning how things work. Chances are you and your kids are, too. ;)

So, here's how the spring scale works:
The more weight that is placed on the scale, the more the spring stretches. Up inside the scale's casing, a needle is attached to the spring. So, when the spring S-T-R-E-T-C-H-E-S, the needle also moves, and points to a particular weight reading. Basic mechanics that have served classroom science activities--and the whole world--well for ages!

Teachers, in your next simple machines lesson, whip out your old spring scale and talk about how it works!