CPT Row 4: What it does vs. Overall Contribution

I am grading a practice PT and am confused about the line between what the procedure does vs. how it contributes to the overall functionality of the program. According to the chief reader notes:

“Describing the function of the procedure and the overall contribution to the program using the same response, i.e. not understanding that the function and the contribution are two separate concepts.”

I have been thinking about it as follows: What the function does is the behavior that is implemented in the function. The overall contribution is how it fits into the broader context of the app/the procedure’s higher level purpose (aside from providing an abstraction)/why the program could not work without it. I have been telling students that they need to explicitly state “It contributes to the overall functionality by…” to make it clear to readers that there is a difference. For example, for a function that recommends a movie to watch, “It contributes to the overall functionality by providing the core decision logic to make a recommendation for the user.” (as opposed to what it does, which is “calculate a movie recommendation based on user inputs and displays that on the screen”)

Some of the samples do explicitly state this phrase or calls out “Without this procedure, the program could not…” However, other sample responses that got row 4 seemed pretty short and unseparated.

E.g. sample E: "The response states what the procedure does to contribute to the overall functionality of the program by stating that the ‘identified procedure decides whether the ball moves forward or if it gets sent back to the beginning based on what color the screen is.’ "

Or Sample G: "The response describes what filter does and how it contributes to the overall functionality of the program: ‘filtering one-by-one through my list in order to output a filtered list that matches the user input.’ "

These seem to describe what the procedure does/high level algorithm for how it works. But how is this also contribution to overall functionality? It seems counter to the idea that they are separate concepts, but perhaps they are 2 ideas in one? Would appreciate some suggestions for how to draw the line for giving them the point for BOTH what it does AND overall contribution vs. not, especially when it’s just a single sentence. Perhaps I’m being too tough on my students, lol?

Hi @eklaka,

Great question! This is a fun one that comes down to semantics. If we look at Sample G, the “what it does” portion would be “filtering one-by-one through my list” and the “overall contribution” would be that it “output[s] a filtered list that matches the user input”.

You’re right – these are closely related but they are not the same exact thing. I like to bake cakes. If someone asked me about baking soda, I’d say that what it does is leavens the batter & adds air bubbles to it. But, its overall contribution is that it makes the cake light and fluffy (rather than dense and rubbery).

The “what it does” is the nitty gritty of the just that – the granular thing the code actually makes happen. The “overall contribution” is why that granular thing is meaningful to the overall program.

Hope that helps,

–Michael K.

Is this what we are thinking:

The function of this procedure is to sort the book title array.

The overall contribution is to enable binary search to find books by title.

Thanks @mkmietowicz ! Makes sense for G.

But what would the contribution be on Sample E? Is it just me, or does “decides whether the ball moves forward or if it gets sent back to the beginning based on what color the screen is” sound like nitty-gritty? :thinking:

Hi @eklaka,

I would say in that case, the function is to decide what to do with the ball, and the contribution is that it moves the game forward by matching the action to the background.

It’s a nitpicky example for sure. Would it be possible for you to link to it so I could read it? I don’t see a Sample E in the current 2021-22 curriculum for CSP Create PT Prep, but I could easily be looking at a different lesson than you are.

Thanks @mkmietowicz , I’m looking at the college board sample e (not code org): https://apcentral.collegeboard.org/pdf/ap21-apc-computer-science-principles-create-performance-task-sample-e.pdf

Commentaries are here:

I think my response from last week is the same, but I’m going to post this now to bump it & ask the community to respond. This one feels like the reader decided they want to split hairs that day.

–Michael K.

Hi @eklaka,

It looks like the College Board is having a webinar on February 22. There’s a Q&A portion so they should be able to help clarify the question above.

If you attend, I think the community here would be interested to hear what they had to say in response to your question. :slight_smile:

–Michael K.

Yeah, I’m signed up and will keep you posted.:). At this point, I’m more concerned about them saying that writing about a filter like the hackathon project could be flagged for plagiarism. (See video posted to CSP exam page around 50 min mark). @mkmietowicz

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