Geometry and algebra can crop up in all sorts of situations.
I was once teaching ESL to a Mexican worker in a limestone factory that made stones for construction, and unexpectedly found an opportunity to teach some math. Part of his job was to make templates for arches. All he was given by the customers was the chord and rise. He needed to know the radius to make the template. He was desperate to learn how to calculate the radius. After some research, I was able to teach him the formula and how to use it. He was beaming. At other times he needed to make templates for ellipses. I taught him how to calculate the distance between foci and how to construct an ellipse with nails, a string and pencil. He was beaming once again.
All this mixes geometry and algebra in the practical world.
I write software for a living, so you could say that I use algebra every day. I mean, what is:
double avgRevenue = totalRevenue / numSold;
if it isn't algebra? Okay, that's a simplistic example that isn't representative of what I really do, so maybe that's just arithmetic with symbols... but wait, isn't "arithmetic with symbols" just a long-winded phrase for "algebra"?
The software that I write deals with statistics, econometrics, linear programming, etc. It's not your average shopping cart application. But even your average shopping cart application contains code with symbolic representations of mathematical equations.
IMHO, this goes back to the idea that, sure, many people will never use anything higher than basic arithmetic in their careers, but if you stop your math learning with basic arithmetic, you've effectively cut yourself off from being a doctor, a pharmacist, a computer programmer, a veterinarian, any sort of engineer, an economist, a patent attorney, and a host of other enjoyable white-collar careers.
It's always nice to have choices.
I knew I forgot an important one. Architects use both algebra and geometry.
from Steve H
I suppose that a high school teacher could argue that (after all of the damage has been done and all of the doors have been closed) there are other things that would help these students for their daily living more than algebra.
However, it would be nice to see these teachers still trying to open doors no matter how closed they seem. With a little more effort on their part, and a willingness of the student to try one more time, the teacher might completely change their world.
This is so much more important than learning to balance a checkbook. By the way, a little algebra will greatly help kids understand how a mortgage (the time value of money) works.
from susan j:
instructivist and googlemaster both did a great job. I would extend the first answer to any building trade or any activity where you use formulas.
Many jobs require setting up and using spreadsheets. Even secretaries need this skill nowadays.
People with cash flow problems may need to use algebra in deciding how to juggle their various accounts.