Wanted: Advice from CS teachers
-
@futurebird I take it there are no assistants in class?
I have no idea if we're talking young adults, high school, or primary. But in high school in the 1980s for grade 12 CS we had to assist in the grade 9 CS class. When a student would raise their hands, one of us in grade 12 would rush over, leaving the teacher uninterrupted.
These are middle school kids. I don't think they need someone to rush over and help them. I want them to think about "my code won't run" in a different way.
-
@futurebird I take it there are no assistants in class?
I have no idea if we're talking young adults, high school, or primary. But in high school in the 1980s for grade 12 CS we had to assist in the grade 9 CS class. When a student would raise their hands, one of us in grade 12 would rush over, leaving the teacher uninterrupted.
Like if someone offered me an assistant I'd say "that's OK." the class size is reasonable 12-18 students. I just need to help them understand errors better.
-
This is helpful for me. I had a hard time understanding why one student was upset, almost to the point of tears (they are very sensitive) that the error message said "error on line 32" but, really the problem was the way they originally named the variable.
"Why couldn't it just say the error was on line 4?
I tried everything I could to fix line 32. 🥺 "My sweet child... it's just not that smart, not like you.
The thing I keep saying is: an error message is not a person telling you what specifically went wrong this time. It's a string somebody writing the program months or years ago thought would describe what they *guessed* back then might cause the code to reach that state unexpectedly.
1. Code can always be wrong, sometimes in ways the programmer hadn't thought of (in fact often since they probably handled the ways they'd thought of) and,
2. Error handling code is code. -
I think they become anxious when their code isn't working the same as what I have up on the projector and they want to get it fixed RIGHT AWAY so they won't fall behind.
Then when one of them starts calling out they all do it.
I may take some time to explain this.
This never happens when I'm teaching math. Something about coding makes them forget some of their manners, and become less self-sufficient. "It's broke! I'm helpless!"
What is that about?
@futurebird When the computer doesn't do the thing when it's supposed to it can be like "why isn't the machine doing what I say?", they're not the source of the issue but the computer can be. When you're the computer, you only have yourself to fix the problem.
-
Wanted: Advice from CS teachers
When teaching a group of students new to coding I've noticed that my students who are normally very good about not calling out during class will shout "it's not working!" the moment their code hits an error and fails to run. They want me to fix it right away. This makes for too many interruptions since I'm easy to nerd snipe in this way.
I think I need to let them know that fixing errors that keep the code from running is literally what I'm trying to teach.
@futurebird Maybe a change of emphasis focussing on "getting it working" as the task, while entering the code becomes a more mechanical step that just has to be done?
-
Example of the problem:
Me: "OK everyone. Next we'll make this into a function so we can simply call it each time-"
Student 1: "It won't work." (student who wouldn't interrupt like this normally)
Student 2: "Mine's broken too!"
Student 3: "It says error. I have the EXACT same thing as you but it's not working."
This makes me feel overloaded and grouchy. Too many questions at once. What I want them to do is wait until the explanation is done and ask when I'm walking around.
@futurebird I’m pivoting off this just to share a funny story. An old CS prof shared this with me when I was staff in a CS department at a university.
One of his undergrads had come to him with a big printed listing of their code (back when that was how you did that! It was probably FORTRAN printed on fan-fold paper). They obviously wanted him to find the problem in their code. It became clear quickly that they hadn’t done anything to debug it themselves.
He started point at various places in the listing. “Right here, add PRINT ‘I am a dumbass’. And here: PRINT ‘I am a dumbass’” and so on. “Then run it and see how many dumbasses you get.”
Now, did he really do that? Is that just how he tells the story? Who knows. But it’s funny. And anyone who has ever written code will agree that this works sometimes.
-
The thing I keep saying is: an error message is not a person telling you what specifically went wrong this time. It's a string somebody writing the program months or years ago thought would describe what they *guessed* back then might cause the code to reach that state unexpectedly.
1. Code can always be wrong, sometimes in ways the programmer hadn't thought of (in fact often since they probably handled the ways they'd thought of) and,
2. Error handling code is code."Error handling code is code."
It had not occurred to me that a student might not see it that way "some guy wrote code to try to tell you what went wrong" but I can see how this might not be how a student might see the errors.
It's like when I realized as a kid that all books are just ... written by people. A revelation. I think I thought, on some level, books were a natural product of the universe. When I realized they could have typos, bad ideas it was so exciting.
-
@futurebird I’m pivoting off this just to share a funny story. An old CS prof shared this with me when I was staff in a CS department at a university.
One of his undergrads had come to him with a big printed listing of their code (back when that was how you did that! It was probably FORTRAN printed on fan-fold paper). They obviously wanted him to find the problem in their code. It became clear quickly that they hadn’t done anything to debug it themselves.
He started point at various places in the listing. “Right here, add PRINT ‘I am a dumbass’. And here: PRINT ‘I am a dumbass’” and so on. “Then run it and see how many dumbasses you get.”
Now, did he really do that? Is that just how he tells the story? Who knows. But it’s funny. And anyone who has ever written code will agree that this works sometimes.
My students are too hard working and sensitive to deserve such things.
But.
Well, I have met other people in my life.
-
Wanted: Advice from CS teachers
When teaching a group of students new to coding I've noticed that my students who are normally very good about not calling out during class will shout "it's not working!" the moment their code hits an error and fails to run. They want me to fix it right away. This makes for too many interruptions since I'm easy to nerd snipe in this way.
I think I need to let them know that fixing errors that keep the code from running is literally what I'm trying to teach.
@futurebird a teacher of mine had a nice trick for this, that I reused when teaching: he would reply "I won't help you until you have drawings of what the code should do, and comments everywhere". Having the students make diagrams (if they didn't start there) helped them find architectural issues in the code logic, and writing comments had them be their own rubber ducks, and forced them to re-read things. In a lot of cases, they figured the issue out before being ready to call ^^.
-
Things to Try:
* look for typos
* look at what the error message indicates.If these don't work consider reverting your last changes to the last working version of your code. Then try making the changes again, but be more careful.
If you can't revert the changes, start removing bits of the code systematically. Remove the things you think might cause the error and run the code again. Isolate the change or code that causes the problem.
You can be a great programmer.
2/2
@futurebird
These two toots should be on a poster in every CS lab! -
@futurebird
These two toots should be on a poster in every CS lab!@futurebird
I once put a sign up in my cubicle that said `What sort of "doesn't work" does it DO?` -
@futurebird a teacher of mine had a nice trick for this, that I reused when teaching: he would reply "I won't help you until you have drawings of what the code should do, and comments everywhere". Having the students make diagrams (if they didn't start there) helped them find architectural issues in the code logic, and writing comments had them be their own rubber ducks, and forced them to re-read things. In a lot of cases, they figured the issue out before being ready to call ^^.
I do this with my older students and with those with more experience. This is the one course that I teach that EVERYONE must take. So there are kids there who have never programmed anything. Kids who were confused when I had them use a computer with a mouse since they'd never seen one in person before.
I'm glad we have such a course. But they just don't know enough to do this yet.
And I have an agenda: I want them to have fun.
-
This is helpful for me. I had a hard time understanding why one student was upset, almost to the point of tears (they are very sensitive) that the error message said "error on line 32" but, really the problem was the way they originally named the variable.
"Why couldn't it just say the error was on line 4?
I tried everything I could to fix line 32. 🥺 "My sweet child... it's just not that smart, not like you.
-
Wanted: Advice from CS teachers
When teaching a group of students new to coding I've noticed that my students who are normally very good about not calling out during class will shout "it's not working!" the moment their code hits an error and fails to run. They want me to fix it right away. This makes for too many interruptions since I'm easy to nerd snipe in this way.
I think I need to let them know that fixing errors that keep the code from running is literally what I'm trying to teach.
@futurebird my student tutor had an annoying habit of answering questions like that with "try doing it right instead of wrong", which was pretty obviously just a way to not get flooded with this exact type of comment.
On the one hand, it's smarmy and unhelpful. On the other hand, sometimes it's useful to tell someone to sit down and not panic in your face so you can continue doing your thing (for their benefit)
-
So Your Code Won't Run
1. There *is* an error in your code. It's probably just a typo. You can find it by looking for it in a calm, systematic way.
2. The error will make sense. It's not random. The computer does not "just hate you"
3. Read the error message. The error message *tries* to help you, but it's just a computer so YOUR HUMAN INTELLIGENCE may be needed to find the real source of error.
4. Every programmer makes errors. Great programmers can find and fix them.
1/
Thanks this is really helpful. We teach a graduate class on quantitative cell biology based in python. Many ppl don’t have prior coding experience, we probably need a section like this.
-
So Your Code Won't Run
1. There *is* an error in your code. It's probably just a typo. You can find it by looking for it in a calm, systematic way.
2. The error will make sense. It's not random. The computer does not "just hate you"
3. Read the error message. The error message *tries* to help you, but it's just a computer so YOUR HUMAN INTELLIGENCE may be needed to find the real source of error.
4. Every programmer makes errors. Great programmers can find and fix them.
1/
@futurebird This is what I would have suggested. Introduce the compiler, explain that you will encounter errors, but the error messages are designed to be as helpful as they can be.
(If you're using Python, error messages have been worked on over the last few major releases, with teaching particularly in mind, so it's worth using the most recent.)
-
Wanted: Advice from CS teachers
When teaching a group of students new to coding I've noticed that my students who are normally very good about not calling out during class will shout "it's not working!" the moment their code hits an error and fails to run. They want me to fix it right away. This makes for too many interruptions since I'm easy to nerd snipe in this way.
I think I need to let them know that fixing errors that keep the code from running is literally what I'm trying to teach.
Test Driven Development can help, although there are skills needed, and you can have errors in your tests!
But the skills needed to write/troubleshoot a good test are more focused/limited than being able to code
Tests also encourage you to write testable code, which is usually modular/functional, and broken code elsewhere is less likely to affect it.
Monolithic code is hard to test/debug.
-
My students are too hard working and sensitive to deserve such things.
But.
Well, I have met other people in my life.
@futurebird Of course. I wouldn’t ever say that to someone trying to learn. But you could tell them the story about the grumpy professor who was a jerk, and they can laugh while learning what printf() debugging is.
-
"Error handling code is code."
It had not occurred to me that a student might not see it that way "some guy wrote code to try to tell you what went wrong" but I can see how this might not be how a student might see the errors.
It's like when I realized as a kid that all books are just ... written by people. A revelation. I think I thought, on some level, books were a natural product of the universe. When I realized they could have typos, bad ideas it was so exciting.
Same with the "average end user":
Your text processor or spreadsheet program also never says "This is the developer writing: I have no idea what you just did, but I didn't expect this."Only "Error 0x8002f0f0: Good luck trying to find out what that means."
-
Sometimes I have them write the code on paper with the computers closed. And this is fine, but I'd rather have them using the IDE or textedit and there is a limit to how much fun you can have with code on paper.
And it does tend to be the weaker students who are almost happy to find something to stop the onslaught of information "see it doesn't work! we can't go on!" and that obviously makes me very grouchy.
I need them to see this is like saying "Teacher my pencil broke! Stop the lesson!"
@futurebird Can I just say: reading this makes me aware what a great teacher you are. Your overall approach and your thoughts about finding the bugs are inspirational. Also they demonstrate in themselves how to try and find the error that causes your students to act differently to their standard.
