Google recently announced its tip calculator:

And of course Siri + WolframAlpha can do the same (along with more advanced math equations):

We continue to outsource mental tasks to our mobile devices. Cue the ‘tech is making us all dumber’ pundits…

As our mobile computing devices evolve to become even easier and more powerful, the question of what math knowledge and skills [or insert other topic here] we still need to memorize and retain in our lives is an open one. And if we don’t memorize certain things, how will we be able to critically analyze and validate the information our devices (or others) give us?

Food for thought this Monday…

I struggled with computation as a kid and then came to the conclusion that I was “bad at math.” Later in HS math, I realized that I was actually good at math, just not computation.

I’m hoping we move to logic, problem-solving and critical thinking. My kids still get math packets for homework and it kills me.

I’ll drag out my standard examples: the Slide Rule, and tables of values (Trigonometric, Logarithmic, etc.)

Not using a slide rule has greatly diminished people’s ability to estimate and keep track of the order of magnitude of their answer. Not using trig tables has diminished people’s sense of the range that their answer should be in. These are useful skills, but most people would agree that the time savings in using calculators is worth the sacrifice.

The flip side is what skills can we use the extra time to instruct? I teach concepts of calculus in an Algebra based Physics course because we

cangraph not only functions, but the motion of objects for which we may not be able to come up with simple formulas. It’s nice to be able to teachwhywe want to find something instead of spending weeks teaching how to calculate it.I don’t believe it is “dumbing” people down. I think it is a tool for those who need it and to be able to use it properly. The key is knowing when it is appropriate. And, as Bill Bradley asked, what should we teach in its place? I don’t find it impressive that someone can mentally calculate a tip (and I can). What I do find impressive is someone who can use the skill (or use the tool to perform the skill) to use to identify and represent what is a meal worth and what was the service worth? I am impressed that someone can determine whether a 20% is a large number or a small number depending of what the 20% is. Understanding the language and social nuances of tipping is more important than calculating it, in my humble opinion.

Gee, I looked at this and saw it as 18% / 6 = 3%. If the total is $89.73, that’s essentially $90, 1% of which is $0.90 and hence 3% of which must be $2.70.

I was “off” by $0.01 due to rounding, and it took me less time than it would to find the app on the phone, start it, and punch in the numbers or even probably to ask Siri. Of course, 20% should be trivially easy with mental math. I have no objection to people using calculators and similar devices for whatever floats their boat, but it’s unfortunate that people don’t know mental arithmetic for the most part.

When you’re doing more complicated mathematics, calculation is often not part of it. But for some things, mental math + mathematical maturity + mathematical intuition + mathematical knowledge are all quite helpful.

And for finding tips, just the first one suffices.

Today’s XKCD comic gives the answer! http://imgs.xkcd.com/comics/simple_answers.png

Thanks for starting my week off with this, Scott. I agree that if we rely solely on tech devices to solve our problems we are practicing very important skills, interpreting and evaluating to understand, but I don’t think there should be a focus on rote skills needed to do simple operations like multiplication and division. Let the technology tools handle that and leave the higher level thinking activities that engage and excite students to want to learn.