Your examples in #139 agree with my contention. The examples make use of correct calculations using rounded or estimated numbers. The numbers are estimated; the calculations are exact.
This started out with 9 x 9 as an example to be estimated. What the sense of estimating that with 10 x 10, or 9 x 10. It’s nonsensical and serves no purpose. And if a kid hasn’t learned the multiplication tables, how can they calculate 10 x 10, or 9 x 10 to make the nonsensical estimate rather than the exact 9 x 9 calculation.
The 9 x 9 example asked for an estimated calculation of exact numbers. Utter nonsense. We don’t estimate the calculation, but we do estimate numbers to be used in exact calculations, as your examples show.
The 9 x 9 test question was an totally asinine exercise for a kid learning math to be asked to answer as some sort of estimate, and it’s not really an estimation. It’s nonsense. Test questions involving real estimates and exact calculations could have been easily developed.
Exactly. The rounded numbers just make the math easier.
The 9 x 9 test question was an totally asinine exercise for a kid learning math to be asked to answer as some sort of estimate, and it’s not really an estimation. It’s nonsense. Test questions involving real estimates and exact calculations could have been easily developed.
I agree. This teacher should find a new line of work ("Would you like fries with that?") if she understands her subject matter so poorly that she thinks 9x9 is a good example for teaching estimation.