# Worst TAing/Teaching experience.

1. Jul 2, 2009

### maverick_starstrider

Hi,

I don't mean to bash hard working undergrads but I would be curious to hear other peoples worst/dumbest/funniest teaching or marking experience.

I'll start things off with a quick one:

-I was once marking the hwk assignment of a first year physics class and one particular student had written something akin to:

$ds=cos(x)\rightarrow \frac{ds}{s}=co(x) \rightarrow d=co(x)$ or in non-LaTeX: ds=cos(x) -> ds/s = co(x) -> d=co(x).

In other words they actually factored the s out of cos (and out of ds). I have to say, I had to stare at that paper for a couple minutes in disbelief.

Anyone else got some good ones?

Last edited: Jul 2, 2009
2. Jul 2, 2009

### Pengwuino

:rofl: :rofl: That's GOLD!

A friend of mine always had this great example of funny things undergrads did. He wrote a quiz and it was mainly give-away points. One question was something like "If a line makes a 90 degree angle with another line, the lines are considered:" and the solutions were A) Perpentangular B) Perpendicular C) Tangentdicular and D) Tangentangular . Of course, people actually picked solutions other then B.

3. Jul 2, 2009

### cristo

Staff Emeritus
At least it was a first year physics class. I've seen similar from second and third years!

4. Jul 2, 2009

### junglebeast

That looks like a case for FailBlog to me if I ever saw one!

5. Jul 2, 2009

### Chi Meson

Most readers of Failblog would not know what was wrong with it.

I kinda weep for that student. He/she probably did really really well in high school physics only to find that the class they took was a watered down physical science class that spent three months on kinematics ("we don't go on until everyone understands what 'acceleration' is").

Probably got an 'A' without ever using a trig function, and so "cos" must have been "displacement x heat capacity x some other variable."

I just had a students who, on three different occasions, in three different assignments (one was even a test) gave a "short response" answer that completely contradicted itself. One was like this (paraphrasing here):

[Question: "Explain why a neutral pith ball will be attracted to a negatively charged rod."]
Answer: "A Neutral pith ball can never be attracted to a negatively charged rod because it is neutral. Only a positively charged pith ball will be attracted to a negatively charged rod. This will cause induction, and the neutral pith ball will be attracted to the negatively charged rod."

6. Jul 2, 2009

### NeoDevin

This was from several 3rd year students:

$i\hbar\geq\frac{\hbar}{2}$

7. Jul 2, 2009

### Topher925

I once had a group of students turn in a lab report where they had written out all of their equations and sample calculations on a white board hanging on someones refrigerator. They took pictures of the white board with the equations written on it and then pasted them into their lab report. They didn't even bother to crop out the pizza coupons out of the picture which were hanging right next to the white board on the refrigerator.

8. Jul 2, 2009

### fleem

Once a student of mine couldn't remember the word "oscilloscope", so they referred to it as a "laboratory television".

9. Jul 2, 2009

### Topher925

HAHA! I'm stealing that one.

10. Jul 2, 2009

### maverick_starstrider

This isn't really my anecdote but does everyone here know the heavy boots anecdote? I tell it to my students sometimes when they make a similar mistake. It basically goes like this:

A professor asks a first year student "Is there gravity on the moon?". The student then thinks on this a bit an replies confidently "No". The professor then asks the student "Really? We've all seen footage of men walking on the moon. How is this possible if not through gravity?". The student, again, sit and ponders a moment before then, again confidently, states "Heavy boots?"

11. Jul 2, 2009

### maverick_starstrider

Oh, I also once had a first year student who I'd never talked to before ask me if I'd give an expert testimony to beat a criminal speed racing charge. They were like "could you tell them that you're a physicist and that, like, them radar guns are really unreliable"... Awkward.

12. Jul 2, 2009

### G01

I have a couple gems from my days as an undergrad tutor:

"Do I really need to memorize both of these formulas for the frequency of an LC circuit:

Formula 1: $$\omega=\frac{1}{\sqrt{LC}}$$

Formula 2: $$\omega=\sqrt{\frac{1}{LC}}$$

I also had a student do the following calculations in an induction problem:

$$\frac{dI}{dt}=$$cancel the d's=$$\frac{I}{t}$$

During an optics problem, I had a student who had trouble finding the correct focal length for a lens:

object distance = 2
image distance = 2

so therefore:

$$\frac{1}{o}+\frac{1}{i}=\frac{1}{f}$$

$$\frac{1}{2}+\frac{1}{2}=\frac{1}{4}$$

Obviously, the focal length was not 4. The student could not figure out why.

Last edited: Jul 2, 2009
13. Jul 2, 2009

### Pengwuino

I'm going to try to use that term as often as possible in my master's project thesis thingy. :rofl:

14. Jul 2, 2009

### junglebeast

It doesn't actually mean the student didn't know how to add fractions. I think we all make silly math mistakes sometimes...just like sometimes I put the cereal in the fridge and the milk in the cupboard

I think it's when something becomes so incredibly easy and basic that the mind stops allocating any actual "thought" to the process and just lets basic instinct take over, which is more of a pattern-matching thing and sometimes matches the wrong pattern...so even when you stare directly at it, you're like...what? It looks right? Because you only see what you are expecting to see.

15. Jul 2, 2009

### Redbelly98

Staff Emeritus
Here's the version of that story that I'm familiar with:
http://www.phys.ufl.edu/~det/phy2060/heavyboots.html
This version is actually contrary to the theme of this thread, as two undergrads are dumbfounded when a philosophy grad TA claims that Heavy Boots are what prevented the Apollo astronauts from floating off into space during their moon walks.

16. Jul 2, 2009

### Pengwuino

This is NOT rare! We've had this story from people in our own university about people in the graduate programs around the campus thinking like that. My immediate response to the heavy boots would have been "What about the Moon's gravity?"... although I have a feeling I would have gotten a response that had to do with the atmosphere...

17. Jul 2, 2009

### bassplayer142

18. Jul 3, 2009

### Moonbear

Staff Emeritus
I agree. I cannot tell you how many times I got an exam question wrong because I would write something like 3x3=6. It's the sort of mistake that it's hard to even catch when proofreading, because your eyes just gloss over it. Those kinds of mistakes just make me cringe and feel sorry for the student.

When I was a TA, we used to have a list of the funniest exam answers we'd pass around and add a few to it each year. I don't remember too many of them anymore.

I haven't seen any really good, funny ones in a while.

19. Jul 3, 2009

### arunma

Here's a funny one. Dang, I wish I'd made a scanned image of this.

When I was TAing the first semester of calculus based physics, there was a homework problem with some electric charge distributed over an arc of a circle subtending a given angle, and the students had to calculate the electric field at the center. A lot of students couldn't do it. But one decided to entertain me instead of just turning in a blank homework. He drew this picture of a "Homework Solving Machine." It was a big monitor with wings on the sides and a funnel on the top. You put the homework in the funnel, press the "solve" button, and then out comes your solution!

I couldn't give him any points, but I had to give him props for that one.

20. Jul 3, 2009

### Astronuc

Staff Emeritus
There are some quantities that must always be positive. One cannot have a negative number of apples, for example. Similarly when solving for a neutron flux in a reactor, one should not get a negative number of neutrons. But I had three grad students calculate a negative flux in a homework problem. They had picked the wrong trigonometric function when solving a second order differential equation because of a misapplication of boundary conditions.

21. Jul 3, 2009

### Pengwuino

Kinda like masses falling upwards in gravitational fields :rofl:

I know one fellow grad student who tends to supply me with great examples of common sense going out the window. You know energies with units of meters or position expectation values that have a 1/x term in it who's limit did indeed blow up.

22. Jul 3, 2009

### Astronuc

Staff Emeritus
or getting negative mass and not realizing that there is something wrong with that.

23. Jul 3, 2009

### Pengwuino

Oh yah! or negative volumes! I'm surprised how common negative masses are.

24. Jul 3, 2009

### rootX

This looks possible (electrons/holes).

Once someone asked me what is recursive function and other time a group of three people didn't know how to integrate a linear line (we had done two calculus courses by that time) but the problem was from other course so they couldn't make connection.

25. Jul 3, 2009

### Office_Shredder

Staff Emeritus