More ideas about gradingEugene Nalence Citation: The Physics Teacher 50, 198 (2012); doi: 10.1119/1.3694061 View online: http://dx.doi.org/10.1119/1.3694061 View Table of Contents: http://scitation.aip.org/content/aapt/journal/tpt/50/4?ver=pdfcov Published by the American Association of Physics Teachers Articles you may be interested in “Small” schools versus “big” schools: Anecdotal notes of a second-year physics teacher Phys. Teach. 50, 509 (2012); 10.1119/1.4758166 From Collaboration to Publication Phys. Teach. 48, 408 (2010); 10.1119/1.3479723 Melba Newell Phillips Award Presentation Phys. Teach. 48, 281 (2010); 10.1119/1.3393049 Peer instruction: From Harvard to the two-year college Am. J. Phys. 76, 1066 (2008); 10.1119/1.2978182 University Teaching Credential Phys. Teach. 44, 406 (2006); 10.1119/1.2353569

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198 The Physics Teacher ◆ Vol. 50, April 2012

letters to the editor

and abstract ideas into focus. But I also believe there are ap-plications for creative thinking that more directly exercise the creativity that is at the heart of good science. In a Modeling Instruction paradigm lab, for example, students might be asked to design their own investigation into the relationship between two variables before that relationship is identified. The creativity required to complete this task is as important as their understanding of the relationship itself.1. Ildefonso (Fonsie) Guilaran, “Creativity and introductory phys-

ics,” Phys. Teach. 50, 42–44 (Jan. 2012).

Joe KremerBrooklyn, NY

discussionphysics.blogspot.com/

More ideas about grading

Grading is such a large part of the job of teaching and is seldom discussed. It was a pleasant surprise to see the excel-lent article in For the New Teacher by Kathleen A. Harper.1

She provided several ideas that both new and experienced teachers will find useful. I would like to offer a few more ideas refined by 41 years of teaching physics to high school students and community college students.

It is clearly necessary to be consistent when grading. This is especially difficult when assigning partial credit to an incor-rectly solved problem. I have found a 40-40-20 rubric to be useful. Forty percent of the point value for a problem solution is awarded for selecting an appropriate equation or relation-ship. Another 40% is awarded for substituting the proper val-ues into the selected equation. The final 20% is given for the correct answer, including proper units and significant figures. When a solution involves vectors, it is appropriate to give the vector part of the answer a point value equal to the numeric part. When a problem solution requires more than one step, the rubric is applied to each step separately. For discussion questions not requiring the use of equations, it is helpful to follow Harper’s suggestion about tabulating all student re-sponses first and then consistently assigning appropriate point values to each answer.

When assigning grades for exams, I think the best pro-cedure is to assign a grade of 100 to the highest raw score attained. All other grades should be a percentage of this high-est raw score. I have never been comfortable with arbitrary scales applied to raw scores to change a grade distribution. In my community college courses, I gave four major tests each semester and only counted the best three test scores in determining the final grade. I found this to be helpful because of situations that might affect a student’s ability to study for a particular test. These might include job requirements, family

Millikan drop on filmThere is yet another alternative for performing the Millikan

experiment not mentioned by Michel Gagnon1 in his article in the February issue of TPT. Disc 3 of Physics: Cinema Clas-sics contains essential nuggets from a PSSC educational film of 1959 sufficient to compute the charge on the electron. Besides a detailed tour of a real Millikan apparatus, there are 12 movie clips of a “falling” latex sphere. The disc player’s frame counter can be used in place of a stopwatch, reducing some of the “te-dious and delicate” aspects of this classic experiment. 1. Michel Gagnon, “Millikan’s oil-drop experiment: A centennial

setup revisited in the virtual world,” Phys. Teach. 50, 98–102 (Feb. 2012).

William M. WehrbeinProfessor Emeritus of Physics

Nebraska Wesleyan Universitywmw@NebrWesleyan University

Screencast software update

In the February 2011 edition of The Physics Teacher, I had an article published entitled “Screencasts for Physics Students” (pp. 84–85). In order to create the screencasts on about three dozen physics topics and problems, I used online software pro-vided by Screentoaster.com. All the videos were supported and stored on Screentoaster’s servers. Unfortunately, shortly after the article was published, this company went out of business and all the videos referred to in my article were lost. I wanted to make sure anyone who is interested in creating screencasts for their students is aware of this, and also provide a few sug-gestions for other software providers to do this type of work.

I now use either Camtasia Studio, for which my school has a license, or a more preferred online service through Screencast-O-Matic, found at screencast-o-matic.com/. This service is incredibly quick and easy to use, and one can upload a screencast video directly to YouTube in a matter of minutes. Some colleagues have begun to use Jing (www.techsmith.com/jing.html) to make their own how-to videos for their classes. I am still in the process of remaking the videos and embedding them on our class blog, as numerous students have been re-questing them for review going into final exams.

Mark VondracekEvanston Township High School

Evanston, IL 60201

Creating creative assignments

I enjoyed reading Fonsie Guilaran’s essay on providing op-portunities for divergent thinking in an introductory physics class.1 As a high school teacher, I’ve found that for many stu-dents, assignments like these can bring seemingly irrelevant

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The Physics Teacher ◆ Vol. 50, April 2012 199

letters

issues, and other pressures that are beyond the student’s ability to control. I also allowed students to prepare a single reference page to use with each test and then allowed them to bring all their reference pages to the final exam. I agree with the com-ments by Samuel Derman2 in his letter where he describes the educational value of having students prepare reference pages.

Finally, I want to emphasize that it is absolutely essential to make at least two forms for every exam. With word process-ing, it is fairly easy to do this. Numeric values can be changed and the sequence of questions can be shuffled. No student should be sitting next to someone with the same test.1. Kathleen A. Harper, “Grading without losing all your time (and

your mind!),” Phys. Teach. 49, 584–585 (Dec. 2011). 2. Samuel Derman, “A final idea,” Phys. Teach. 49, 533 (Dec. 2011).

Eugene NalenceFizix01@yahoo.com

Correction: Max Ziegler, “Overhead Projector in a Wastebasket,” Phys. Teach. 50, 60 (Jan. 2012).

The second, unnumbered, equation should read h (2R1 – h) = r2.

Cartoon: © by Allan Cedeno, Costa Rica.

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