"What is the additive inverse of 2.5?" would also test knowledge of vocabulary. |
"opposite" direction on a number line seems more obvious and intuitive than "additive inverse" |
Checked with a mathematician. He laughed. Opposite is not a math word. My 7th grader did not learn opposite as a math vocab word. One can infer what it probably means (opposite linearly wrt zero). This is an example of some person who doesn't understand math making up a ridiculous question. That's all. It doesn't demonstrate any mathematical knowledge whatsoever. Again, guessing what the person who wrote the test wants you to say.
Wouldn't it be better to ask an arithmetic question or useful numberline question instead? Something to demonstrate, does this child know how to add, or subtract, or move about the number line? |
Some person who doesn't understand math, for example Sal Khan: https://www.khanacademy.org/math/algebra2/complex-numbers-a2/complex_numbers/v/complex-conjugates-example |
LOL! Just asked by DH. He asked: Do you mean "inverse"? Never heard "opposite" at MIT. |
I can't paste it. It says:
Point P is plotted on the number line. (Shows point at 2.5; shows number -4 to 4 plotted). Point Q is the opposite of Point P. Determine the location of Point Q on the number line. Explain how you determined the location of Point Q on the number line. |
OK what is your point here? I just wasted 4 minutes watching this video. He says the numbers have opposite signs. That is correct terminology. If the question asked what number has the opposite sign that would be fine. Asking what the opposite is without specifying with respect to what makes no sense. Sure, many kids, maybe most, could figure out what the person who wrote the question wanted, but it's not mathematically correct. Do you want your kids being taught and tested on knowing mathematical truth or that math can be anything you want? |
Well, if DH never heard it at MIT, then obviously it doesn't exist! No, wait... http://www.montereyinstitute.org/courses/Algebra1/COURSE_TEXT_RESOURCE/U02_L1_T1_text_final.html (I bet he never heard about "regrouping" or "composition/decomposition" at MIT, either.) |
OK, so Point Q is at -2.5, because -2.5 + 2.5 = 0. |
It's a matter of how the person asking defines their terms. The word opposite doesn't mean anything mathematically by itself.
So this ends up being a question about the teacher. Did the teacher teach the arbitrary definition of opposite that we decided we want them to teach since we like making up new terminology in math rather than teaching real concepts with existing words? So rather than test actual mathematical knowledge they are teaching the memorization of arbitrary and meaningless definitions. What a waste. |
The diff is that Monterey defined their term. Using terms like regrouping is ok for teaching but they are a means to an end, not an end in itself. Testing should be about knowledge of subject matter. |
+1 I immediately asked my husband about this. He's a PhD physicist (Northwestern University) and he said exactly what your mathematician friend said. It's not a math term. He had never heard it used that way either. My feeling is that many math people are not necessarily good "word" people (I live with one). But if they are given a problem, they can solve it and show that they can pass math. |
+1 |
Monterey used the term in the same way that the PARCC test question did. Therefore, the PARCC test question did not make up the idea. Also, math subject matter includes math vocabulary. |
http://www.njspotlight.com/stories/15/03/17/state-officials-testing-firm-asked-to-explain-disturbing-monitoring-of-student-tweets/ State Officials, Testing Firm Asked to Explain ‘Disturbing’ Monitoring of Tweets John Mooney | March 17, 2015 Assembly education committee chairman looks askance at surveillance of Twitter accounts for possible PARRC security breaches Calling the practice “disturbing,” the chairman of the state Assembly’s education committee has asked representatives of Pearson and the state Department of Education to explain their monitoring of student social media account. The testing company state officials have said that Twitter posts had been checked for potential security breaches related to the state’s PARCC testing. State Assemblyman Patrick Diegnan (D-Middlesex) said yesterday that he has heard conflicting accounts about the monitoring, which led the state to warn at least two districts of possible test-security issues. He asked Pearson and the Christie administration to send representatives to the committee’s meeting on Thursday to further explain the process. |