“I have to defend the teaching of estimation. It’s a useful tool to quickly check the reasonableness of calculated answers. Marking 9x9=81 as wrong for an estimate is the correct thing to do. (It is, though, a poor example to use for teaching estimation. The kid should have already been taught that by memorizing the ‘times table’.)”
Wow, this is a new definition. The estimate is in the calculation? I constantly used estimates in business over many years, but the estimates were estimated results CALCULATED EXACTLY. Never heard of estimated calculations.
And I’m confident the estimated calculations are total nonsense, of little or no value in the real world of business, science, or any other field.
Sounds like just another made up method to give a passing grade to students who can’t pass when exact answers must, be, er, exact, as in real world math applications.
But any time time you want me to make change for you, I’ll be happy to do it using estimations.
No it's not a new definition. It may be different from the one you're using but it isn't new. Are you referring to estimates that you provide to prospective customers? If so, you're right, the estimate is fully calculated from the best information available.
In grade-school math classes, though, an estimate is a quick approximation of the answer to a complicated calculation. If that approximation says that the result should be around 100 and your calculated answer is over 300, you immediately know that your result is suspect.
I disagree. I use estimations all the time when shopping.
If I have only a limited amount of money with me at the time, I keep a running total of estimates in my head to see just how much I can buy on that trip.
It also has allowed me to catch mistakes in pricing or the way the cashier rang up an order.
One time the bill came up about $20 off what I had estimated and when the cashier checked the receipt, it turned out someone had entered the wrong amount into the computer system for green beans and was charging about $50 a pound for them.
When I was getting my degree, my science professors encouraged us to use estimates to see if we were close in our answers.