37
Similar to @Vince, I think it's a good practice to do both. I don't really agree with the cooking recipe analogy, though. Pseudocode describes that the algorithm does, without going into detail how you do it.
I think perhaps a better analogy:
Pseudocode: you need to put an egg into the flour mixture
Actual code: pick up an egg, crack it open on the side of ...
36
As someone who has now taught CS for many years, let me first reassure you that teaching clear, clean coding is entirely worthwhile. I think this is especially true for those who will not go off into software professionally, because editing, and being able to express ideas in a clean, clear manner is a skill that serves people well in any field. (I've ...
26
Actually I am of the opinion that you should not present your own code, but rather get the students to implement the algorithms you teach them, which you give in pseudocode, and give them the freedom to choose any one of a fixed set of languages that you are familiar with, such as C++/Java/Python. Really, the only way students can truly understand an ...
17
Rather than giving them processes to model algorithmically, have them start coming up with algorithms for everyday activities. Here is the formal assignment I have students complete: CS50 AP - Everyday Algorithms.
They begin with a simple pseudocode example:
1 look out the window
2 if it is raining outside
3 put on your rain boots
4 put on ...
13
How do you teach students of this age and ability to think algorithmically?
I don't really think there's a silver bullet to this problem. To be able to think algorithmically, you need to solve lots of problems, over and over. Some students will naturally have the ability to be able to describe algorithms without much teaching, but it's not a universal skill,...
13
Back around 1985, Susan Merritt created an Inverted Taxonomy of Sorting Algorithms. The idea is that to sort an array you have two phases, the split phase and the join phase. She divided the various algorithms into two types easy split/hard join and hard split/easy join varieties. Merge sort is of the former type. Quick sort is the latter.
But all sorts, ...
10
Neither is always better, and both have their strengths.
The idea of scoring higher marks as a criteria for better is going to be unpredictable without knowing who is granting those marks. Someone who is heavily in favor of one style over the other may grant higher marks to low quality uses of their favored style than they would to high quality answers in ...
9
Homework problems in algorithms classes often involve finding clever tricks that the professors find elegant or interesting
That seems like a strange way of teaching algorithms. It shouldn't involve trying to make the students recreate brilliant ideas from scratch (most people won't re-invent Dijkstra's algorithm when asked to find the shortest path through ...
9
Actually, the code is terrible, but I don't think its purpose is to illustrate a stack so much as to illustrate in a very rudimentary way how heap allocation works. (Worse than "terrible", it isn't "pythonic").
But you are wrong about the efficiency. Only the initialize function is O(n). Push an pop are O(1) as should be obvious.
But no serious code ...
8
I think it's really about breaking down the concepts into smaller pieces. First a student needs to understand recursion well, then they can understand memoization and dynamic programming. It's hard to just jump into e.g. the knapsack problem without first having worked through simpler problems. After one gets practice with the basic concepts, dynamic ...
8
The Wirth formula, Algorithms + Data Structures = Programs is still valid. It is also complete. A program is nothing more than algorithms acting on data structures. That formula does not make explicit the difference between a bad, error-riddled program and a good, error-free efficient program. Looking at the formula, however, can show how to improve the ...
7
The problem as described is simply translation from one firm of words to another, so in some senses, students may not really grasp what you are asking for. I think a more important thing to ask for is to construct algorithms from a less structured problem.
A flow chart is just another way to write the algorithm, not really a progression - and not ...
7
I usually teach Uniform Cost Search (UCS) before A*, since it is basicaly A* without the heuristic (and it reduces to BFS when all costs = 1, so it is pretty straightforward to explain). Then I teach A* and show them animated examples of the explored nodes in comparison to UCS (here you can find excellent interactive examples).
In this step, one analogy I ...
7
Since all the other great answers are all given, let me mention a minor one. Lateral thinking Puzzles are good for this. They help to teach children to think in a different manner by themselves and encourage general problem solving.
However, they can be used to teach one important part of algorithms, the need for rigor in your statements, if one chooses ...
7
I'm a bit confused by your question. Your exercise seems to involve some combination of…
Requirements gathering: what are the inputs, outputs, and formulas?
Translating the requirements to a conceptual model
Translating the conceptual model to pseudocode
Translating the pseudocode to code
Translating the pseudocode or code back to a flowchart (Why? In ...
7
Thinking algorithmically isn't always natural. In an algorithm, you're going to write down everything the computer is going to, then hit "go" and step away for a few microseconds while the computer does it. In most of our lives, there's more back-and-forth in our interactions, so it takes a while to get used to thinking in this one-pass approach.
...
7
I remember a demonstration from early in my first college CS course (this was in 1998, almost 20 years ago!), where the professor brought in a loaf of bread, a butter knife, a jar of peanut butter, and a jar of jelly. He then asked the class to give him instructions to make a peanut butter sandwich, with predictably hilarious results. After we had finally ...
7
The Dutch National Flag problem is linear in running time. Essentially sort an array with only 3 distinct values each of which may appear 0 or more times. (not length 3). You are allowed only one pass over the array, so the solution is a single while loop with some prior initialization.
It was probably originally posed by Dijkstra. It is mentioned in David ...
7
A variant on the ENIGMA machine encryption works well in a single loop, and is sufficiently complex to give students a real challenge.
The core idea of the ENIGMA machine for this assignment is that (1) a number is given as an initial key, and (2) every prior letter used influences how the next letter will be encrypted.
So, use a modular circle of ...
7
The simplest example that still bears enough complexity to show what's going on is probably merge sort. It's no coincidence that this algorithm is the classical example to begin explaining the divide and conquer technique.
I am not sure at what level you teach, but your students should be comfortable with both recursion and inductive proofs before venturing ...
7
I emphasize readability and maintenance of code. Therefore, I will assign a project and later turn around and require another student to complete the second half of it. Everyone ends up maintaining someone else's code as a result.
I think you should continue teaching your good habits and thinking styles. That said, you see a student doing Olympiad problems ...
6
Sounds like you've tried everything already, but here are some suggestions:
Use a scenario / problem that every student can relate to
Most of my lower ability 13-14 year old boys don't have much experience of wages, tax and jobs. Writing an algorithm for making a perfect cup of tea doesn't do much for them either. Drawing a flow chart for how to irritate ...
6
I had zero experience with algorithms when I started. Here are a couple of things I wish had been done differently.
Let Students Make Mistakes
My TAs and professors always tried to guide me to the best answer, show me the right "trick", or stop me from making a mistake before I actually made it. Whenever I'm helping someone out with CS now, I usually let ...
6
Pseudocode helps a lot by removing anything unnecessary, and focusing entirely on the algorithm, which can already be hard to understand as is. It's also faster to express ideas : if a student wants to write a different algorithm than the one you taught them, it can be really cumbersome if they have to deal with every details of Java.
As others said, it's ...
6
Buffy is provably correct (no risk needed!) that it is impossible to do it with automated code analysis, as this is an attempt to figure out when a program will finish (i.e. the halting problem.)
You can get a very good guess, however, by using a few (very) differently sized input data sets, run the program on each one multiple times, and observe the ...
5
I have a contrary view. Dynamic programming and it's close cousin memoization are actually pretty easy to teach. It's true that students frequently struggle mightily with dynamic programming, but I strongly believe that it's usually not the actual dynamic programming that they're struggling with, but rather the underlying recursive relationships. If I ...
5
You could show them the results with a given heuristics function, that has a single parameter which impacts how the heuristic function affects the cost estimate.
As an example,
estimate = D * (horizontal_distance + vertical_distance)
where the distance is the one between the current node and the goal (quite straight forward in a maze, albeit not such a ...
5
I just finished up 8th grade.
I took an Intro to Engineering/Robotics class as an elective this past semester. I have programmed (mainly in Python 3) before this class, and I was mainly excited for the Robotics part. When we started, the teacher talked to us about how the computer takes things very literally, etc, etc, and then - he had us pretend he was ...
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