I AM FURIOUS WITH THE NEW COMMON CORE BASED MATH WORKBOOKS
In my daughter’s homework a few weeks ago, she had to do addition and subtraction of four-digit numbers. Part of her assignment (per the workbook) was to CHECK her work. The workbook said it was OK to use rounding to determine if her answers were REASONABLE. The workbook did not say to check to make sure her answers were CORRECT.
Here’s an example: If you add 1,111 and 7,777 you get 8,8888. According to the workbook, to check your work, you round to the thousands. So, you add 1,000 and 8,000 to get 9,000. Since 8,888 rounds to 9,000 it’s good enough. Any answer from 8,500 to 9,499 would be considered reasonable according to the workbook.
I told my daughter, in our house we check our work the old fashioned way. We make sure the answer is CORRECT. I made her go back and check her work using the real method to make sure her answers were CORRECT. Making sure your answer is REASONABLE is what will get you fired in the real world. I can’t wait until we get bridge engineers doing truss calculations and being happy when the calculations are REASONABLE instead of CORRECT.
I am perfectly fine with kids being taught how to estimate by rounding. I am not OK with my daughter being told rounding is an acceptable way to check your work. REASONABLE IS NOT OK. This “feel good” math is a disaster.
Here’s a photo of the same crap in my son’s math workbook.
P.S. Let me reiterate. I am 100% in favor of teaching kids to round numbers (preferably the common way most of us learned and not they way they taught my daughter to do it for checking her work). I just don’t think rounding to check your work is acceptable. I’m sorry, but “reasonable” is not correct and that doesn’t constitute a check in my world. Rounding is a great way to estimate mow much money you need to take to the grocery store. Rounding is not a great way to make sure your answer is correct.