Dear colleagues,
Regarding our last meeting, please find below extensive details regarding how to grade the first Homework for CS101.
> If needed, please also find again the few slides asking these problems.
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> There is a lot of details in this email, please try to read, practice and understand all of it, *if you think you need it*.
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## What deadline?
Let us try to have ALL the grades by **next Wednesday**, so we can try to give back the homework as soon as possible (on the next lab, next week), before the first Mid-Term exam.
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## Who grades what?
- I take my two groups (**A1**, **A4**: I have all the answers),
- *Prof. Vipin* takes his two groups (**A2**, **B2**: he still have to collect the last answers),
- *Prof. Thiyagarajan* (assisted by Prof. Kondaiah) takes two of his groups (**A3**, **B4**, still have to collect B4 tomorrow, A3 next Monday),
- *Prof. Arya* and Prof. Vivek takes the last groups (**B1**, **B3**, still have to collect B1 next Monday).
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## Marking scheme to follow
Please find attached two examples of answer papers, corrected in red color by me, and scanned.
I propose the following marking scheme (can be modified if you think it needs to) :
- 20 total marks.
- 3 marks for [Pb1](http://goo.gl/xwN89a), 6 marks for [Pb2](http://goo.gl/rIFW8p), 3 marks for [Pb3](http://goo.gl/3m6Wgl), 5 marks for [Pb4](http://goo.gl/UH6pjZ), and 2 marks for [Pb5](http://goo.gl/Wkdoq4) + 1 bonus point.
> In details, I suggest this:
### [Problem 1:](http://goo.gl/xwN89a)
- 1 mark for input values *x, y*
- 1 mark for $x_{min} < x < x_{max}$ and $y_{min} < y < y_{max}$
- 1 mark for the good output ("Inside" or "Outside")
### [Problem 2 (the harder):](http://goo.gl/rIFW8p)
- 1 mark for the good input for *x, y*
- 3 marks for how to compute the equation of the line (*ax+by+c*) / the z-component of the cross product $( \mathbf{PQ} \times \mathbf{PA} ) . \mathbf{z}$ (cf. my last email for more math. details about that test)
- 2 marks for the correct output regarding the sign of *ax+by+c* (if they used the equation of the line) / of the cross product (be sure to check if they did not mess up the sign and the direction, printing left when it should be right or the opposite)
### [Problem 3:](http://goo.gl/3m6Wgl)
- 1 mark for computing the distance with the good math formula ($d = \sqrt{ (x-x_c)^2 + (y-y_c)^2 }$)
- 2 marks if the three cases of the output are good (on the circle if $d = r$, outside if $d> r$, inside if $d < r$)
### [Problem 4:](http://goo.gl/UH6pjZ)
- 2 marks for explicitly computing the 3 equations for AB, BC, CA / or computing the z-component of three different cross-product
- 2 marks if they say which values have to be positive for the point to be inside the rectange
- 1 mark for the good output
### [Problem 5:](http://goo.gl/Wkdoq4)
- 2 marks, as you like. Basically, 2 if they did it in a way *you understand*, 0 otherwise.
### Bonus !
Finally, I suggest a last +1 point if the student did good drawings and/or a good presentation.
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## More details about the solutions, and their respective Python programs
If you need more detail about the solution, please find attached one Python program that solves each problem; or in the .zip archive file, one file for each problem.
> (you should be able to execute it on your laptop, or on any on-line Python 2 interpreter, as http://repl.it/languages/Python or http://pythontutor.com/visualize.html).
### Practice your Python!
For example, for the problem 1, please consult the page http://repl.it/9NX for all the problems.
> Or click on these links: http://goo.gl/xwN89a for a visual demo of the execution of the program for problem 1.
> http://goo.gl/rIFW8p for problem 2, or http://goo.gl/3m6Wgl for problem 3,
> http://goo.gl/UH6pjZ for problem 4, and http://goo.gl/Wkdoq4 for problem 5.
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## How / Where to input the grades?
As discussed, let us try the built-in feature of Moodle for this.
Please go to that page (http://www.mahindraecolecentrale.edu.in/portal/grade/report/grader/index.php?id=27) as soon as you are done grading your group(s).
Then, log-in with usual id/password, select your group, and click on "Turn editing on".
Finally, you can add all the grades for your group, and click on save.
> - If this fails, we will go back to using a basic XL sheet.
> - If you lost your ID or password, I will create a new one for you.
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Happy grading !
--
Lilian
Subject: How to grade the first CS101 Homework : marking schema and more [CS101]
To: Profs. Arya, Vipin, Lilian, Thiyagarajan
CC: Profs. Kondaiah, Vivek, Dhande, Didier
CCi: Prof. Lilian