[jdeisenberg]

I have never liked the “make a sandwich” task. It sets people up for failure, because the teacher can always take things literally enough to make the student wrong. (For example, when given the instructions: "Take out two slices of bread", the teacher can rip open the side of the plastic bag rather than use the opening.) Some students end up with the feeling of “If I can’t even explain how to make a sandwich, how will I ever be able to tell a computer to do anything?”

Here’s an exercise (not sure where I discovered it) that I use at the community college level: https://www.youtube.com/watch?v=meSK1rn2VbA It has the same elements of analyzing a problem, breaking it into steps, and making sure they’re in the right order; but it’s set up for students to succeed.

This exercise is very effective when you put the students in groups of two or three to work on it.

[kazinator]

Sounds like this make a sandwich exercise is rather good for understanding the issues with gathering software requirements; it confronts the students with creeping requirements, before they even know how to code.

Coding should probably be taught with a background of requirements that are precisely given in terms of the abstractions that are being used in the code. So that is to say, the problem itself doesn't have to be something abstract (like a number-theoretic computation); it can be connected to something in the real world. But the representational mapping from that domain to the computer should be established by the teacher, so there is no irrelevant fumbling about the requirements.

In the case of the sandwich, we should provide a procedure which somehow takes the slices of bread out of the bag. Similarly, we provide all other necessary procedures, and only those procedures are to be used. Then we eliminate questions about the detailed requirements about what those procedures themselves do, like can the bag be ripped, or does the removal have to be tidy.

A good domain for teaching coding might be game playing (cards, etc). People understand that the objects used in games are abstract, and that certain details do not matter to the game, like the exact shape of a rook in chess or its precise placement within a square. It could just be the letter "R" in an 8x8 grid of characters (with "r" being the opposite color).

Symbolic games are basically a form of mathematics that is instantiated in the real world whose abstractions people readily understand. Moreover, they have a point (to have fun), so the "why are we doing this" question is settled.

[otterpro]

That video was super-helpful. I believe he is a CS instructor, and his methods are easy to explain and understand, unlike a lot of class that just rush the students into learning bunch of technology before really learning how to think like a programmer.

Also there's his follow up video where he solves the puzzle (https://www.youtube.com/watch?v=z5VKyKvgyRs). Another helpful video is him teaching how to go through a program by hand, using pen and paper (https://www.youtube.com/watch?v=9Ahejeuasf0)

[pbhjpbhj]

The whole point of the exercise is for the teacher to do it in an unexpected manner. The exercise is about established structures and constraints, isn't it?

The point being "I can't even tell someone how to make a sandwich without establishing the platform we're building on". If you start a python app writing in assembly or Fortran then (in general, you pedants!) it's not going to work.

If you do the same exercise with cooperative people then you don't normally emphasise the point because they do a lot that's not clearly defined, and that hides the point about defining the parameters and metrics you're working with.

[disqard]

Thank you for sharing this video. It can be more helpful for novices than the flat-out adversarial approach of "I'm going to mess this sandwich at every possible step to show you that you need to be precise".

I've found that learners will succeed when they are able to answer affirmatively these two questions: "can I do this?" (self-efficacy), and "do I want to?" (motivation).

The robot scenario with a handful of commands is preferable compared to the "make me a sandwich" task in both respects, because failing badly at even getting bread out of the bag (say) can destroy both self-efficacy and motivation.