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RE: Geometry Rubric Scoring Clarification  # 37
Posted:
Jun 24, 2011 9:08 AM



We worked on finding the points of intersection with the calculator. We used the graphing tools as well as the table where the y values coincided. This issue points out what I stressed with my kidsthat graphing by hand is only as good as your ruler or your curve sketching ability. It falls short very quickly when dealing with curves or problems using 'real' values for slopes and intercepts. It was quite unreasonable to expect students to get an exact value of .5 when sketching a parabola. The key should have included something like 'accept reasonable answers'. I didn't correct that question but would have been very tempted to allow .7 if the students curve crossed a bit above the middle of that line. I certainly would have accepted it in class if they were required to do the problem by hand.
Neal
From: ownernyshsmath@mathforum.org [mailto:ownernyshsmath@mathforum.org] On Behalf Of Amy Sacca Sent: Friday, June 24, 2011 8:41 AM To: nyshsmath@mathforum.org Subject: Re: Geometry Rubric Scoring Clarification  # 37
I called the state about this, and they definitely would not budge and told me that "Students should be able to see that the parabola and line intersect at exactly half way between the lines, and should always check their answers anyway. Even still, they have a graphing calculator with the capabilities to use that to calculate the point of intersection."
Amy
>>> <TKENYON@crcs.wnyric.org> 6/24/2011 8:33 AM >>>
Oh, and the parabola line intersection  I never in a million years expected noninteger values. We had a lot of students ignore the point of intersection that wasn't a "nice" point. I'm not 100% sure how the students actually would be expected to find the intersection graphically, particularly since points of intersection can have irrational values. Using a table of values is not graphically. And although it's a "graphing calculator", using the button to find the point of intersection is not "finding it graphically" either. Although, apparently, in the future I'll have students use the calculator to calculate the point of intersection, then just pretend they found it graphically. We had a student guess that the xvalue was .7 instead of .5, because that's about where it intersected on her graph. That was a 99%.
Tom Kenyon CRCS Mathematics/Physics tkenyon@crcs.wnyric.org
ownernyshsmath@mathforum.org wrote: 
To: nyshsmath@mathforum.org From: TKENYON@crcs.wnyric.org Sent by: ownernyshsmath@mathforum.org Date: 06/24/2011 07:48AM Subject: Re: Geometry Rubric Scoring Clarification  # 37
The only thing that bummed me out about the geometry was the problem with the measures of 3 arcs given as a ratio. To solve for the arcs, we'd see 12x=360, x=30. Then, quite a few students filled in the diagram with the correct arc measures  150, 120, 90 degrees, and then wrote down "30 degrees" for the answer. Even though the arithmetic is trivially simple for many students, since they didn't write down (15090)/2, our grading team only gave 2 points, because "how do we know they didn't think the angle was just x." I don't know if I had more than 1 student not have 30 degrees for the answer, but many lost 2 points for not showing that work. The rubric states that 150, 90, 120, but no further correct work = 2 points. I tried calling and calling and calling state ed, but the line was always busy. Grades were due, we had to make a decision. *sigh*. 1 student shy of 50% mastery though, so I was relatively happy with my results. Tom Kenyon CRCS Mathematics/Physics tkenyon@crcs.wnyric.org
ownernyshsmath@mathforum.org wrote: 
To: nyshsmath@mathforum.org From: "loretta boyce" Sent by: ownernyshsmath@mathforum.org Date: 06/24/2011 07:21AM Subject: Re: Geometry Rubric Scoring Clarification  # 37
The linear quadratic system question: if they listed one point OR the other without work they receive 0 credit. If they listed both points of intersection without work, they receive 1 credit.
Loretta
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