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+# VG151 — Midterm 1: A Chronicle
+
+(All timezones are UTC+8)
+
+## 2022-10-19 10:00, Zoom
+
+The ENGR151 teaching team (TT for short) gathered online for our first
+exam preparation. At first we thought the exam would be online and spent
+an hour thinking of ways to prevent cheating, as there has never been an
+online coding exam. We have a few questions on their project (for example
+how did you plot your rectangles in matlab) that would be super easy to
+cheat on, so Manuel proposed an oral exam (as was tried on international
+students who attended this course online constantly).
+
+Fortunately, this exam model was never tried because we got news that next
+week will be offline again, after more than one month of lockdown.
+
+The exam consists of two parts: part A is on paper, and part B is coding.
+We created a Gitea issue to track our ideas for part B.
+
+## 2022-10-19 11:08, Gitea
+
+One TA submitted their idea to the thread. It's about [Sierpiński
+triangles](https://en.wikipedia.org/wiki/Sierpi%C5%84ski_triangle). I know
+where they found it: [the Wikipedia article on recursion, section "In
+Mathematics"](https://en.wikipedia.org/wiki/Recursion#In_mathematics).
+
+![Evolution of a Sierpiński triangle](img/vg151_e1/sierpinski.png)
+
+## 2022-10-19 16:46, Gitea
+
+Another idea emerged. It was about a basic line interpreter that takes
+a file of definitions of shapes (position, size, color, etc) and plots
+them accordingly.
+
+## 2022-10-19 17:47, Gitea
+
+And here's my idea: I was taking discrete math, and in set theory they
+have this trick where you represent a natural number `n + 1` with `n
+U {n}` (where `U` stands for union). So, if we take 0 to be the empty set
+`{}`, 1 is `{} U {{}} = {{}}`, 2 is `{{}} U {{{}}} = {{}, {{}}}`, etc etc.
+Here's my code:
+
+```
+function set_theory
+        n = input('Input a natural number: ');
+        disp(n2s(n));
+end
+
+function s = n2s(n)
+        % convert natural number to set theory representation
+        if n == 0
+                s = '{}';
+                return
+        elseif n == 1
+                % handle edge case where we need no comma
+                s = '{{}}';
+                return
+        end
+
+        s1 = n2s(n - 1);
+        % pretty much a hack: strip the trailing },
+        % push s1, and put the } back
+        s = [s1(1:end-1) ', ' s1, '}'];
+        return
+end
+```
+
+I thought it was a simple exercise, almost _too_ simple as long as you
+know how recursion works.
+
+## 2022-10-20 13:06, Gitea
+
+Manuel has read all our ideas, and decided to go with two:
+
+- The shape interpreter, and
+- My set theory recusive algorithm
+
+However, he commented that the interpreter needs to be more challenging,
+and that he will remove the set theory notation from mine in favor of
+something else, but it remained a mystery at the moment.
+
+## 2022-10-20 17:15, Gitea
+
+Babe wake up, new interpreter specifications just dropped
+
+We added:
+
+- `compose` instruction that works like classes
+- fill colors
+- absolute or relative movement
+
+## 2022-10-21 21:15, Mattermost
+
+Manuel put together an early draft of the testpaper for us to check. There
+are three exercises:
+
+- One exercise about the shape interpreter
+- One exercise about some alien sci-fi in the Minami-ke lore
+- One exercise about RGB image manipulation
+
+The sci-fi goes like this: (paraphrased)
+
+Minami Haruka shows her sisters a weird device she found with a keypad and
+a screen. When she presses 0, screen reads `-.`; 1 → `--..`,
+2 → `--._--...`, and 3 → `--._--.._--._--....`.
+
+Kana suspects that aliens are using this device to "communicate as they
+plan to invade campus", but Haruka found a pattern. What pattern?
+
+`-` is `{`, `.` is `}`, and `_` is `,`.
+
+Now that the lore is over, the questions are
+
+- What is 4
+- Diagram of recursion
+- Base case
+- Steps repeated
+- Describe algorithm
+- Implement algorithm
+- What is 12
+
+I admire Manuel's imagination that exploded an innocent set theory
+notation to make such a bizzare scenario.
+
+Also, another side effect is, the order of this sequence is well-defined.
+No need to worry about `{{}, {{}}}` and `{{{}}, {}}`.
+
+## 2022-10-22 19:28, Mattermost
+
+Manuel sent us his semi-ready version of the testpaper, on which
+I discovered a flaw:
+
+> Convert from hexadecimal into binary: 16, AG.
+
+I reported it to Manuel, expecting him to fix it:
+
+> pretty sure `AG` isn't a hex number
+
+Here's how he replied:
+
+> `AG` i know this is not hexadecimal, but do they? :smirk\_cat:
+
+> I like tricky questions...
+
+> when they ask us duirng [sic] the exam we just tell them if they think
+> there is a mistake they explain it
+
+At this moment I knew our students are about to be bamboozled. We'll wait
+and see…
+
+Also, there was a sample output image for the shape interpreter exercise.
+On the screen it looks like this (cropped so I don't get sued):
+
+![A color image with green, yellow, cyan, red and black
+](img/vg151_e1/graph_color.png)
+
+However, I'd imagine the paper would be printed in grayscale, which means
+it will look like this:
+
+![Grayscale of previous image; everything is either black or the same
+shade of 50% grey](img/vg151_e1/graph_hsv.png)
+
+Manuel changed the grayscale method to HSL (Hue, Saturation, Luminance) so
+it looks better:
+
+![Still grayscale but colors are distinct](img/vg151_e1/graph_hsl.png)
+
+## 2022-10-23 11:00, Mattermost
+
+A few more typos and ambiguities are fixed, but there came another
+problem: the image Manuel asked students to manipulate, `forest.tif`, is
+part of an image processing toolbox, so we switched to `corn.tif` to be
+safe.
+
+## 2022-10-23 17:19, Mattermost
+
+The exam papers are ready for printing.
+
+## 2022-10-26 13:18, Gitea
+
+I created e1 repos for everyone and drafted an announcement for testtakers
+to clone it.
+
+## 2022-10-27 13:50, UEO
+
+Menako got the exam papers in a bag from UEO.
+
+## 2022-10-27 15:45, exam room
+
+We had 85 students — 78 of which took the exam offline. We had 44 in our
+exam room, the rest in another.
+
+We unsealed the package of testpapers, and found this thing:
+
+![Grayscale image, but now the sun is also black and fused into the
+road](img/vg151_e1/graph_printed.png)
+
+As a fix, when part B began we would project the image we intended on the
+screen.
+
+## 2022-10-27 16:00, exam room
+
+The bell struck and the exam commenced. Little did they know, they were in
+for a big surprise. Hands in the room I proctored rose in confusion.
+"Excuse me," one asked, "this question doesn't look quite right to me."
+
+I asked, "what's the problem with it?"
+
+They replied, "I don't think `G` is a—"
+
+"Just write down what you think. Manuel's probably thinking the same
+thing."
+
+Participatory exam: an exam where students are not the only ones taking
+it; instead, proctors play a major part in maintaining the effect of trick
+questions. We indeed tried very hard not to spoil it.
+
+It's official folks, exam proctoring is a performance art now.
+
+## 2022-10-27 16:30, exam room
+
+Time for part B. I walked around, and was amazed by the multitude of
+laptop models in the modern age. I guess half-tablet half-keyboard C-sides
+are a thing now?
+
+At least three testtakers got confused halfway through exercise 3, waved
+at me and asked "what's the corn image?" I shrugged and told them to read
+on.
+
+## 2022-10-27 17:35, exam room
+
+One testtaker raised a question:
+
+In exercise 1 (shape interpreter) we provided some sample code to be
+interpreted. One line goes
+
+```
+square background cyan (0,0) 20 20
+```
+
+Another goes
+
+```
+square road black (0,-5) 10
+```
+
+Obviously they are off by one parameter. Turns out the specification and
+the second line were changed, but the first one wasn't. We ended up
+issuing an erratum 10 minutes before the exam ends.
+
+## 2022-10-27 17:45, exam room
+
+It's time to submit everything to Gitea. I had a flash drive in case
+someone's antenna melts, but it turned out unnecessary. The process was
+simple as `git add ./; git commit -m 'e1'; git push` then opening
+a release called `e1` on Gitea.
+
+We collected and counted the exam papers, then dismissed the exam.
+
+## 2022-10-27 17:57, exam room
+
+All e1 repos are archived. As our room was mostly empty, we went ahead to
+the other room which Manuel was a proctor of.
+
+I assigned myself to exercise 2 of part B, because that's the way karma
+works; I contributed the idea after all. So did the TA who made exercise 1.
+Menako assigned herself to most of Part A, and expected to begin grading
+that night.
+
+Discussion rooms in Longbin Building, the official building of Joint
+Institute, were not open for booking, so we had to use Manuel's office. He
+handed Menako his key. It was the rarest of in-game items, uncraftable by
+any means.
+
+## 2022-10-27 18:37, McDonald's
+
+The rest of the TA group had plans that night so Menako and I had burgers
+at McD's, then rode off to Longbin Bldg.
+
+## 2022-10-27 19:00 or something, Manuel's office
+
+Manuel's office is tiny. Crappy monitor, crappy keyboard, but many chairs
+and a bookshelf of math textbooks.
+
+Exercise 2 was the only one in part B to require answers on paper or the
+README file, so the first thing I did was to classify the answer sheets
+based on where they wrote them. That night I graded everything on paper,
+but wasn't able to read all the README files.
+
+Menako, on the other hand, graded part A with blazing efficiency. What
+quickly grabbed our attention was how she should grade the `AG` question.
+After some discussion, we agreed upon this rubric:
+
+- If you think `G` is 16 (or any other number), you get zero points.
+- If you leave this question blank, you get full marks.
+- If you explain that `G` is not a hexadecimal digit, you get full marks
+  plus a star (no points, but it's a token of prestige).
+
+She finished her part that night.
+
+## 2022-10-27 23:00 or something, [undisclosed location]
+
+I need to come up with a way to grade the last question (what is 12)
+without going through the trouble to scan through all 10,239 characters
+(that's how long it is). And the solution? Checksum.
+
+I grep'd everyone's README.md for >10k-character long sequences of `-_.`,
+piped them to md5sum, then sorted them. The command is
+
+```
+$ grep -hoE '[-_\.]{10000,}' FILE.md | md5sum
+```
+
+There were 7 different versions:
+
+- One is empty;
+- One is correct;
+- One is correct if you strip one dot (they wrote it in a markdown ordered
+  list) from the beginning;
+- One is truncated at 10k characters because they copied it from the
+  variable window instead of command window. No point for you, sorry.
+- The other three are incorrect.
+
+Subsequently I spent a dozen minutes committing the grades with a red pen
+on paper. As this question is worth one point, I just treated it as
+atomic.
+
+That night I also graded all the README's.
+
+## 2022-10-28 12:55, Manuel's office
+
+The next day I went back to Manuel's office again, this time to get things
+done for once and for all. All my colleagues came along (except Menako).
+The desk was crowded but fortunately I'm mostly done with paper, so I took
+a corner to grade all the code.
+
+My rubrics are based on four criteria:
+
+- Base case (2pt)
+- Recursive case (3pt)
+- Coding style (1pt)
+- Your code doesn't crash (1pt)
+
+Yes, if your code is unindented or looks like a mess, I will take away one
+point.
+
+And there are two special rules:
+
+- Iterative algorithms get no point
+- Marginally recursive algorithms get 4pt max.
+
+What counts as marginally recursive? Well, consider this Python snippet:
+
+```
+def alien(number, string, target):
+    if number == target:
+        return string
+    string = string[:-1] + "_" + string + "."
+    return alien(number + 1, string, target)
+
+print(alien(1, "--..", 3))
+```
+
+Does it work? Yes. Does it yield the correct result? Yes! Is it recursive?
+
+…Maybe?
+
+I mean, it *does* call itself. But it's not what we meant! Observe how
+`number` grows larger and `string` longer as we go to the deeper level.
+Recursion as we taught in the lectures was the opposite: breaking down the
+problem until it falls within the base case(s). Furthermore, this is tail
+recursion, which is just iteration with extra steps.
+
+
+## 2022-10-28 16:42, Manuel's office
+
+Part A is finished for all paper submissions.
+
+## 2022-10-28 17:09, Manuel's office
+
+Part A is finished for international students also.
+
+## 2022-10-28 20:21, Manuel's office
+
+Grading finished for the whole exam.
+
+## 2022-10-28 20:34, Mattermost
+
+We begin discussing curves. Manuel remarked:
+
+> no rush to publish grade. you graded too fast!!
+
+and
+
+> fastest 101/151 grading ever!!! :partying_face:
+
+We decide to delay the release, at least not until the next weekday.
+
+## 2022-10-29 10:02, Mattermost
+
+Remember on 2022-10-23 we switched to `corn.tif` for Part B ex3 "to be
+safe"? Huge mistake. It turned out, `corn.tif` wasn't an RGB image as we
+thought it was — it was an _indexed_ image, which means it comes in two
+parts:
+
+- A list of key-value pairs of color indexes and RGB values
+- A matrix of indexes
+
+To convert it to RGB, you need to call `ind2rgb`. At first this was part
+of our rubric, but after a while we found it too harsh, so we just awarded
+points to whoever processed it correctly as if it were RGB.
+
+## 2022-11-01 09:00, Canvas
+
+Grades are released. Paper checking is scheduled at 2022-11-03
+20:20-22:20.
+
+## 2022-11-03 20:00, meeting room
+
+I arrived at the meeting room reserved for the paper checking session and
+laid out the testpapers. A few eager students were waiting outside.
+
+As time went on, the room became increasingly crowded. A line appeared by
+my side, asking for points.
+
+The single most asked question is:
+
+> Why did I get zero for "write an algorithm"? I wrote it in my code!
+
+For context, we have two contiguous subquestions:
+
+- Write an algorithm describing how the conversion works
+- Implement the algorithm in matlab
+
+Both were assigned 7 points, so you see the importance of the former. What
+I was expecting was:
+
+- A piece of text
+- Pseudocode
+- Comments in code
+
+Sadly, many assumed "my code is self-documenting, it answers both
+questions." Sorry, you're misinterpreting what we meant by an algorithm.
+
+There was one case though, I forgot to check someone's README file
+somehow, and wasn't aware they wrote pseudocode. I read it, and it made
+all the sense I wanted to see. Ka-ching, 7 points. The same person had
+their Part B ex1 grade bumped by 6 points (grade looked like 10, but was
+actually 16). That's 13 points in total. _So lucky._
+
+## That's a wrap!
+
+This is everything that (a) I feel like sharing and (b) I am allowed to
+share.