Unit 3 · Programming 2 · Lessons 3.22–3.24 · Practice PT

Create PT: Build Days

Three days to build your program, prove it meets all four code requirements, and capture your Personalized Project Reference. Individual work — this is your rehearsal for the real thing.

Big Idea 3 — Algorithms & Programming3 build days · individual

This page is your build checklist. Your approved idea from 3.21 is the plan; this page keeps you honest against the requirements while you code. Verify specifics against the current CED for your exam year.

Where We Are

People→ Bits→ Programs→ Internet→ Security→ Big Data→ Impact

Still in Programs. Idea approved (3.21); now you build. The one question that matters all three days: which requirement does this code satisfy? If you can’t answer it for a chunk of code, that chunk isn’t earning points.

The Three-Day Plan

Pace yourself

Day 1 — make it run. Get the skeleton working: your list, your procedure stub, and a call. It doesn’t have to be smart yet; it has to run.

Day 2 — make it right. Put real selection and iteration inside the procedure, make it return something useful, and use that result in the main program. Test on a few inputs.

Day 3 — capture it. Record the short video of your program running, and take the screenshots for your Personalized Project Reference (PPR) — your list and your procedure with its call.

The Requirements Self-Audit

Check each box only when you can point to the exact lines in your program that satisfy it. “It’s in there somewhere” does not count — on the PT you must cite the code.

List: a list stores data my program actually uses (not a leftover variable). Procedure with parameter: I wrote a procedure, and changing its parameter changes what it does. Selection: there is an if inside that procedure doing real work. Iteration: there is a loop inside that procedure. Call: my main program calls the procedure and uses what it returns. It runs without errors, and I can state its purpose in one sentence.

Check a box only when you can point to the lines that satisfy it.

Your Personalized Project Reference (PPR)

The PPR is the small packet of code screenshots you bring to the written responses. You need exactly two things captured clearly:

Capture on Day 3

□ Your list — the line(s) where it’s created and used, clearly readable.

□ Your procedure — its full definition (with the parameter, the selection, and the iteration visible) and the line where it’s called.

Also record a short video (about a minute) of your program actually running — input to output. If it doesn’t run on video, it doesn’t count, so save time on Day 3 for this.

Common Point-Losers — avoid these

Loses points

A procedure with a parameter it never actually uses · a loop or if outside the procedure instead of inside it · a procedure that only prints, so the main program can’t use its result · a “list” that’s just one value.

Earns points

A parameter that visibly changes the output · selection and iteration living inside the procedure · a return whose value the caller uses · a real list the program reads or traverses.

The return-vs-print trap (3.13) is the most common one. If your procedure prints instead of returns, the main program has nothing to “use,” and you can lose the call point. Make your procedure return its result and let the main program decide to print it.

Impact Check

Self-auditing against a spec is the actual profession

“Which requirement does this code satisfy?” is not a school question — it’s what every engineer asks against a spec, a contract, or a checklist before shipping. Building something and then proving, line by line, that it meets each stated requirement is the job. The PT is a small, honest rehearsal of it.

Connections

Came from 3.21 — your approved, scoped idea is what you’re building.

Uses all of Unit 3 — list, procedure, parameter, selection, iteration, call — assembled at last.

Next in 3.25 — timed written responses about the exact program and PPR you finish here.

Returns for real — the real Create PT is this, with more time and higher stakes. The habits you build now carry straight over.