1. Reference Guide

Comparisons — these are what make a condition

Each one evaluates to True or False, and nothing else.

Operator	Question it asks	Example	Result
==	are these equal?	amount == 0	False when amount is 500
!=	are these different?	sender != "mom"	True when sender is “unknown”
> <	bigger / smaller?	amount > 100	True when amount is 500
>= <=	bigger or equal / smaller or equal?	score >= 9	True when score is 9
in	is this inside that?	"gift card" in message	True when the words appear

= and == are not the same thing. = stores a value. == asks a question. Mixing them up is the single most common error in this topic.

The shapes

Shape	Outcomes	When to use it
if alone	1 answer, 2 outcomes	Almost never. One outcome is silent.
if / else	2 answers, 2 outcomes	A yes-or-no decision.
if / elif / else	3+ answers	Ranges or levels, ordered narrowest first.

Boolean operators — from 3.5, used here

Operator	True when	Example
and	both sides are True	asks_for_money and not known_contact
or	either side is True	has_link or asks_for_money
not	flips it	not known_contact

Every command in this lesson, in all three languages

This is the table to keep open. Everything this lesson uses, side by side. Working versions of rows 8–15 are in section 5 under E. The same decision in JavaScript (a live runner you can press Run on) and F. The same decision in College Board pseudocode — not just listed here.

What you want	Python	JavaScript	College Board pseudocode
Store a value	x = 5	let x = 5;	x <- 5
Is equal to	x == 5	x === 5	x = 5
Is not equal to	x != 5	x !== 5	x NOT= 5
Greater / less	x > 5, x < 5	x > 5, x < 5	x > 5, x < 5
Greater or equal	x >= 5	x >= 5	x >= 5
Is inside	"a" in text	text.includes("a")	not in the reference sheet
Booleans	True False	true false	true false
If	if x > 5:	if (x > 5) {	IF (x > 5)
Otherwise if	elif x > 3:	} else if (x > 3) {	nested ELSE + IF
Otherwise	else:	} else {	ELSE
Both true	a and b	a && b	a AND b
Either true	a or b	a \|\| b	a OR b
Flip it	not a	!a	NOT a
Show something	print(x)	console.log(x)	DISPLAY(x)
Show what is inside what	indentation	{ }	{ }
Comment	# note	// note	// note

The three rows that catch people out.

= versus == flips meaning between Python and pseudocode. In Python, = stores and == asks. In College Board pseudocode, <- stores and = asks. So a pseudocode x = 5 is a question, and a Python x = 5 is an instruction. Same characters, opposite jobs.

Pseudocode has no elif. A chain of three or more answers is written as IF / ELSE blocks nested inside each other. Python’s elif is shorthand for exactly that structure, which is why an exam question can look deeply indented when the Python equivalent is flat. Section 5D shows the same four answers written both ways.

JavaScript’s === is the one to use. JavaScript also has ==, but it converts types before comparing, so "5" == 5 is true. Use ===, which does not.

College Board pseudocode connections

Pseudocode	Python	Python example	When you reach for it
IF (condition)	if condition:	if score >= 9:	One thing to check, one thing to do
IF / ELSE	if: / else:	if x: ... else: ...	Exactly two answers, both written down
IF inside ELSE	elif	elif score >= 6:	Three or more answers in a range
Boolean expression	comparison	amount > 100	Building the condition in the first place
AND / OR / NOT	and / or / not	a and not b	One condition from two questions

Mistakes this lesson is about

Mistake	What it looks like	Fix
if with no else	Prints nothing, raises nothing, exits 0	Give every condition both answers
= instead of ==	SyntaxError, or a silently wrong condition	= stores, == asks
elif chain in the wrong order	Runs, prints, and is wrong. Later branches unreachable	Order thresholds narrowest first
Comparing different types	TypeError: '>' not supported	int("10") before comparing to a number

2. LxD Cycle Process

Empathize

We found the misconception in our own course material. The 2025 lesson for this topic opens with a conditional that has no else:

if (time < 3 && score > 1000) {
    lives = lives + 3;
}

Run it with time = 4.2 and nothing happens. No error, no warning, no output. That lesson flags it a moment later — “Problem: What if the conditions aren’t met?” — so the person writing it already knew.

The gap isn’t knowing that branches can be missing. It’s noticing one is missing in your own code. That’s hardest in Python, where a program with a missing branch runs to completion and exits with status 0. Success and “did nothing” look identical from outside.

While building this we found a second failure that is worse, and that almost nobody teaches: an elif chain in the wrong order. It is never silent. Every input produces confident output. Some of that output is wrong, and two of the branches can never run at all.

Define

• POV: A CSP student needs a way to check that a conditional covers every case and that every branch is reachable, because neither failure produces an error — one prints nothing and the other prints something confidently wrong.
• Learning goal: Students will build conditions from comparisons, give every condition all of its answers, and order an elif chain so no branch is unreachable.

Ideate

• HMW: How might we make a wrong conditional visible before it runs, when neither failure raises an error?
• Activity — count the answers, then check each branch is reachable. Two questions you ask on paper, in that order.
• One scenario, two failure modes. The capstone scam trainer, first failing silently and then failing loudly and wrongly.

Prototype & Test

Built as this notebook, taught to our team, then revised. What changed is in sections 7 and 8.

3. College Board Requirements

AP CSP Big Idea 3, Topic 3.6 Conditionals. Learning objective AAP-2.H: express an algorithm that uses selection.

Essential knowledge for this topic covers:

• Algorithms can use selection to decide which statements run, based on a Boolean expression.
• An IF statement runs a block only when its condition is true; an IF/ELSE statement runs one block or the other, so exactly one of the two always runs.
• A Boolean expression evaluates to true or false and is built from comparison and logical operators.

The counting method in this lesson is how we check that a selection structure actually covers what it claims to. College Board pseudocode for the full elif chain is in section 5.

Verify the exact wording and page numbers against your own copy of the CED before quoting it on an assessment. We are citing the objective, not a page.

4. Lesson Plan

Learning Objective

By the end of this lesson you can build a condition out of a comparison, give every condition all of its answers, and order an elif chain so that no branch is unreachable.

Success Criteria

• You can look at an expression like amount > 100 and say what it evaluates to before running it.
• Every input to your conditional produces output. Nothing falls off the end.
• You can look at an elif chain and say whether any branch can never run.

One rule for the whole lesson: a condition is a question that always comes back True or False, and every question needs all of its answers written down.

One scenario for the whole lesson. Every example and hack on this page is the same program: the scam-message trainer from our Friends of Poway Seniors capstone. A message arrives and the trainer decides what to tell an older adult about it.

Open a notebook before we start. There are two Popcorn Hacks here and you do them while we teach. Copying each finished one into your own portfolio notebook is your job, not ours. The frontmatter you need is in section 6.

This lesson is one condition at a time. When two conditions need four different answers, that is nesting, and it is a separate topic.

How the lesson goes

We build one idea at a time, and you run code after each one.

1. A condition is a question. Comparisons like amount > 100 produce True or False. That value is the condition.
2. Example A — an if with no else, and the output it does not produce.
3. Popcorn Hack 1 — you fix a conditional that is silent for half its inputs.
4. Example B — an elif chain with four answers, ordered highest threshold first.
5. Popcorn Hack 2 — you fix a chain whose order makes two of its branches unreachable.
6. and / or / not — combining two questions into one condition.
7. The same decision in JavaScript and College Board pseudocode.
8. Homework Hack, which you do at home rather than here.

Transfer the Popcorn Hacks yourself. We are not collecting them here. Paste each finished one into your own portfolio notebook as you go — section 6 has the frontmatter.

Tech Talk

A condition is any expression that evaluates to True or False. That is the whole definition.

Most conditions are not handed to you as True or False already. You build them out of a comparison:

amount > 100          # a question about a number
"gift card" in text   # a question about text
sender == "mom"       # a question about equality

if runs a block only when the condition is True. else runs when it is False. elif asks another question, but only if every condition above it was False — which is the thing that makes order matter.

Why counting matters here. In most languages a missing case is just wrong. In Python it is wrong and silent: if x: with no else, and x false, prints nothing, raises nothing, exits 0.

The count. One condition has 2 outcomes, so it needs 2 answers. A chain with 3 thresholds has 4 outcomes, so it needs 4 answers. Count the outcomes on paper, count the prints in the code, and compare.

5. Code Examples

Each example is followed by the Popcorn Hack that checks it. Do the hack before we move on.

	Example	What it shows
A	Building a condition	comparisons produce True / False
B	One condition, no else	the silent missing answer
	Popcorn Hack 1	you fix it
C	Four answers with elif	ordering thresholds
	Popcorn Hack 2	you fix the order
D	and / or / not	one condition from two questions
E	The same decision in JavaScript	runnable, same four answers
F	The same decision in College Board pseudocode	exam form, no elif

A. Building a condition — a question that answers True or False

Before any if, look at what a comparison actually produces. Every line below prints True or False and nothing else. That value is the condition.

Code Runner Challenge

3.6 - Comparisons make conditions. Every line prints True or False.

View IPYNB Source

# CODE_RUNNER: 3.6 - Comparisons make conditions. Every line prints True or False.

message = "URGENT: send $500 in gift cards today to unlock your account"
amount_requested = 500
known_contact = False

print("gift card" in message)      # is that text inside the message?
print(amount_requested > 100)      # is the number bigger?
print(amount_requested == 0)       # is it exactly zero?
print(known_contact)               # already a yes/no fact, no comparison needed
print(len(message) > 200)          # is the message unusually long?

Python Java JavaScript Pseudocode 14px 16px 18px 20px

Lines: 1 Characters: 0

Output

Click "Run" in code control panel to see output ...

Notice the fourth line. known_contact is already True or False, so it needs no comparison. The other four are built by comparing two things. Both kinds are conditions — anything that lands on True or False can go after if.

Watch == versus =. amount_requested == 0 asks a question and produces False. amount_requested = 0 would store zero and destroy the value.

B. Example A — one condition, and the answer that isn’t there

The trainer’s first version. If a message mentions gift cards, warn the user.

Run it before reading on.

Code Runner Challenge

3.6A - One condition: run it, what prints?

View IPYNB Source

# CODE_RUNNER: 3.6A - One condition: run it, what prints?

message = "Hi Mom, are we still on for Sunday?"

if "gift card" in message:
    print("Careful - this message is asking for gift cards.")

Python Java JavaScript Pseudocode 14px 16px 18px 20px

Lines: 1 Characters: 0

Output

Click "Run" in code control panel to see output ...

No output. No error. Skimming past it, you would assume it worked.

One condition means 2 possible outcomes. Count the answers: there is 1. The other outcome falls off the end of the program and disappears — and a scam trainer that says nothing is worse than no trainer at all, because to the person reading it, silence looks exactly like “this message is fine.”

One else fixes the silence:

Code Runner Challenge

3.6A - One else: now every outcome gets an answer

View IPYNB Source

# CODE_RUNNER: 3.6A - One else: now every outcome gets an answer

message = "Hi Mom, are we still on for Sunday?"

# 1 condition -> 2 outcomes -> 2 answers
if "gift card" in message:
    print("Careful - this message is asking for gift cards.")
else:
    print("No gift card request in this message.")

Python Java JavaScript Pseudocode 14px 16px 18px 20px

Lines: 1 Characters: 0

Output

Click "Run" in code control panel to see output ...

Popcorn Hack 1 — the silent failure

A different condition in the same trainer. This one checks the amount of money a message asks for. Someone wrote the case they were picturing and stopped.

Step 1. Run the cell below without changing anything. Answer in chat: what does it print, and is that an error or a bug?

Step 2. Fix it so both outcomes print, and add a count comment above the if in this form: # 1 condition -> 2 outcomes -> 2 answers

Step 3. Paste your fixed code in chat, then copy it into your own notebook.

Code Runner Challenge

3.6 Popcorn 1 - Run it first. Then make both outcomes print.

View IPYNB Source

# CODE_RUNNER: 3.6 Popcorn 1 - Run it first. Then make both outcomes print.

amount_requested = 0

if amount_requested > 100:
    print("This message is asking for a large amount of money.")

Python Java JavaScript Pseudocode 14px 16px 18px 20px

Lines: 1 Characters: 0

Output

Click "Run" in code control panel to see output ...

C. Example B — more than two answers, with elif

Two answers is often not enough. Our trainer scores each message from 0 to 10 and gives advice that matches how bad it is.

Three thresholds means four outcomes, so we need four answers. Watch the order: highest threshold first.

Code Runner Challenge

3.6B - Four answers from one number, highest threshold first

View IPYNB Source

# CODE_RUNNER: 3.6B - Four answers from one number, highest threshold first

risk_score = 9

# 3 thresholds -> 4 outcomes -> 4 answers
if risk_score >= 9:
    print("Do not reply. This is almost certainly a scam.")
elif risk_score >= 6:
    print("This looks risky. Check with someone you trust before replying.")
elif risk_score >= 3:
    print("Be a little careful, but this is probably fine.")
else:
    print("Nothing suspicious in this message.")

Python Java JavaScript Pseudocode 14px 16px 18px 20px

Lines: 1 Characters: 0

Output

Click "Run" in code control panel to see output ...

Count the answers

risk_score	Which branch runs	What the trainer says
9, 10	if	Do not reply
6, 7, 8	first elif	Check with someone you trust
3, 4, 5	second elif	Be a little careful
0, 1, 2	else	Nothing suspicious

Four outcomes, four answers. Every possible score from 0 to 10 lands somewhere, and the final else is what guarantees it — there is no score that falls off the end.

Why the order is what it is. elif only gets asked when everything above it was False. So by the time Python reaches risk_score >= 6, it already knows the score is under 9. That is why >= 6 means “6, 7 or 8” here and not “6 or anything above.” Each branch quietly inherits the failures of the ones above it.

Try it: change risk_score and re-run until you have seen all four answers.

Popcorn Hack 2 — the chain in the wrong order

Same four answers, same four thresholds, nothing missing. This one is not silent — every input prints something. It is still broken.

Step 1. Run it without changing anything. risk_score is 9, the worst score a message can get. Answer in chat: what does the trainer tell that person?

Step 2. Harder question: which branches in this code can never run, for any score at all? Name them.

Step 3. Fix the order, paste it in chat, and copy it into your own notebook.

This is the one to remember. Counting answers does not catch it — there are four answers for four outcomes. You have to check that each branch is reachable.

Code Runner Challenge

3.6 Popcorn 2 - Run it first. Then fix the order.

View IPYNB Source

# CODE_RUNNER: 3.6 Popcorn 2 - Run it first. Then fix the order.

risk_score = 9

if risk_score >= 3:
    print("Be a little careful, but this is probably fine.")
elif risk_score >= 6:
    print("This looks risky. Check with someone you trust before replying.")
elif risk_score >= 9:
    print("Do not reply. This is almost certainly a scam.")
else:
    print("Nothing suspicious in this message.")

Python Java JavaScript Pseudocode 14px 16px 18px 20px

Lines: 1 Characters: 0

Output

Click "Run" in code control panel to see output ...

D. Combining two questions — and, or, not

Briefly, because these belong to 3.5 Booleans. We use them here; that lesson is where they get taught properly.

They let you build one condition out of two. and needs both sides True, or needs either side, not flips one.

Code Runner Challenge

3.6C - and / or / not, used to build one condition

View IPYNB Source

# CODE_RUNNER: 3.6C - and / or / not, used to build one condition

asks_for_money = True
known_contact = False

print(asks_for_money and known_contact)   # both must be True
print(asks_for_money or known_contact)    # either one is enough
print(not known_contact)                  # flips it

# 1 combined condition -> 2 outcomes -> 2 answers
if asks_for_money and not known_contact:
    print("A stranger is asking you for money. Treat it as a scam.")
else:
    print("Not a stranger asking for money.")

Python Java JavaScript Pseudocode 14px 16px 18px 20px

Lines: 1 Characters: 0

Output

Click "Run" in code control panel to see output ...

The limit of and, and where this lesson stops. asks_for_money and not known_contact gives you exactly two answers: that one combination, and everything else. It cannot tell “only asks for money” from “only a stranger” from “neither.” When those need four different answers, you need a conditional inside a conditional — and that is 3.07 Nested Conditionals, not this lesson.

E. The same decision in JavaScript

Identical logic to Example B — same four answers, same order. Only the punctuation changes: braces instead of indentation, else if instead of elif.

Code Runner Challenge

3.6B JS - The same four answers in JavaScript

View IPYNB Source

%%js
// CODE_RUNNER: 3.6B JS - The same four answers in JavaScript

let riskScore = 9;

// 3 thresholds -> 4 outcomes -> 4 answers
if (riskScore >= 9) {
    console.log("Do not reply. This is almost certainly a scam.");
} else if (riskScore >= 6) {
    console.log("This looks risky. Check with someone you trust before replying.");
} else if (riskScore >= 3) {
    console.log("Be a little careful, but this is probably fine.");
} else {
    console.log("Nothing suspicious in this message.");
}

Python Java JavaScript Pseudocode 14px 16px 18px 20px

Lines: 1 Characters: 0

Output

Click "Run" in code control panel to see output ...

F. The same decision in College Board pseudocode

This is the form the AP exam uses. <- is assignment, = is the equality test, DISPLAY is output, and braces group a block.

riskScore <- 9

IF (riskScore >= 9)
{
    DISPLAY("Do not reply. This is almost certainly a scam.")
}
ELSE
{
    IF (riskScore >= 6)
    {
        DISPLAY("This looks risky. Check with someone you trust before replying.")
    }
    ELSE
    {
        IF (riskScore >= 3)
        {
            DISPLAY("Be a little careful, but this is probably fine.")
        }
        ELSE
        {
            DISPLAY("Nothing suspicious in this message.")
        }
    }
}

Read the indentation. College Board pseudocode has no elif, so a chain of four answers is written as IF / ELSE boxes inside each other. That is the same structure Python’s elif is a shorthand for — which is worth knowing before you see it on the exam and assume it is something new.

What to notice across all three. Python uses indentation, JavaScript uses braces, pseudocode uses nested ELSE blocks. None of that changes the decision. Counting outcomes, counting answers, and checking each branch is reachable works identically in every one.

6. Hacks & Practice Tasks

Prepare your submission IPYNB

Two minutes. Do this once and the two Popcorn Hacks have somewhere to live.

1. Create a new notebook in your portfolio under _notebooks/homework.
2. Make the first cell a raw cell and paste the frontmatter below. This is the submission frontmatter — it is not the same as the frontmatter on this lesson page.
3. Paste each of your two finished Popcorn Hacks into its own code cell, keeping # CODE_RUNNER: as the first line.
4. Add the Homework Hack below them.

5. Run every cell, confirm the output, then publish.

   ---

   layout: post codemirror: true title: 3.6 Conditionals HW categories: [Python] lesson_language: Python lesson_topic: Conditionals HW lesson_part: interactive lesson_type: lesson permalink: /python/conditionals-hw author: yourGithubID —

codemirror: true is the one people leave out. Without it every code editor on your page renders as an empty box.

Where the Python runner gets its answers. On a published page it calls the shared class server at flask.opencodingsociety.com, and you do not start anything. When you preview locally at localhost, it calls localhost:8587 instead, so you have to be running the backend yourself or every Run says “Failed to fetch.” Start it from your backend repo — not your portfolio, which has no main.py:

source venv/bin/activate;python main.py

Leave it in its own terminal. The JavaScript runner never calls either server, so it works regardless.

Homework Hack — build the trainer’s scoring step

Do this at home, in your own notebook. There is no runner for it on this page on purpose — the two hacks above were the interactive part.

Right now risk_score is just handed to us. Your job is to compute it, then report on it.

Here is the starting point to copy into your notebook:

# CODE_RUNNER: 3.6 Homework - score a message, then advise on it

message = "URGENT: send gift cards now to unlock your account"
amount_requested = 500
known_contact = False

risk_score = 0

# TODO 1: add to risk_score using conditionals, one signal at a time
# TODO 2: report on the final score with an if / elif / else chain
# TODO 3: count comment in this form, with your real numbers:
# N thresholds -> M outcomes -> M answers

Your task:

1. Score the message. Use a separate if for each signal, adding to risk_score: +4 if the message mentions gift cards, +3 if the amount asked for is over 100, +2 if the sender is not a known contact. Say in a comment why each of these does not need an else.
2. Report the score with an if / elif / else chain of at least four answers, ordered so no branch is unreachable.
3. Add the count comment above the chain, in the form above, with your real numbers.
4. Prove every branch is reachable. In a markdown cell, give one set of input values that reaches each answer. If you cannot find inputs for a branch, that branch is dead code — fix the order.
5. Test the extremes. Run it with a completely clean message and with one that trips every signal. Both must print something sensible.

Stretch, not graded: your scoring uses if with no else on purpose, which is the exact thing Example A called a bug. Explain in one sentence why it is fine here and not there.

Submission safety rules — read first

• Keep # CODE_RUNNER: as the first line of every code cell.
• Your code must run in the code runner with no errors.
• Every outcome must print() something. A branch that does nothing is the bug we are grading against.
• Use if / elif / else only. No match, no dictionaries of functions, no one-line ternaries.
• No import and no input() — the runner cannot type answers for you.

Submit your work

1. Put both Popcorn Hacks and the Homework Hack in your own notebook, run every cell, and confirm the output.
2. Commit and push, then open the published page and confirm it loads.
3. Paste your finished Homework Hack code into the submission form at the bottom of this lesson.
4. In the notes, include the URL of your published page and the line: 3.6 Conditionals popcorn + homework complete.

The form takes code, but the published notebook is what the Popcorn Hack points are read from — do both.

Grading Plan — 1 point total

0.2 — Popcorn Hacks, transferred to your notebook

Points	Criterion
0.1	Popcorn Hack 1 — both outcomes print, count comment present
0.1	Popcorn Hack 2 — order fixed, and the unreachable branches correctly named

0.8 — Homework Hack

Points	Criterion	What we look for
0.2	Scoring step	A separate if per signal, with a comment explaining why no else is needed
0.2	Reporting chain	At least four answers, else at the end, every score from 0 upward lands somewhere
0.2	Reachability proof	One set of inputs per branch, in a markdown cell
0.1	Count comment	Present, correct, matching the number of answers actually in the code
0.1	Extreme tests	Clean message and all-signals message both run and print

Quick validation checklist

• Present: # CODE_RUNNER: as the first line of each cell.
• Present: both Popcorn Hacks, fixed, in your own notebook.
• Present: a count comment above the reporting chain.
• Present: a print() in every branch.
• Present: a markdown cell proving each branch is reachable.
• Absent: any input that produces no output.
• Absent: a branch no input can reach.
• Absent: match, ternaries, import, input(), or errors when run.

If the Run button says “Failed to fetch”

The Python runner is not running your code in the browser — it sends it to a server. Which server depends on where you are:

You are viewing	It calls	If it fails
a published page	flask.opencodingsociety.com	the shared class server is down; not something you can fix
localhost preview	localhost:8587	your own backend is not running

For the second one, start the backend from your backend repo with source venv/bin/activate;python main.py. Your portfolio folder has no main.py — running it there gives No such file or directory.

The JavaScript runner executes in the browser and calls neither server, so you can always check your logic there while the Python side is down.

7. Lesson Revisions

Revision 1. Rebuilt on one scenario that grows, rather than restarting with a new story every example — the scam-message trainer from our Friends of Poway Seniors capstone, which is the part of the project this logic runs in. Added the same decision in JavaScript and College Board pseudocode.

Revision 2 — hacks restructured. Our draft had one Popcorn Hack parked at the bottom next to the homework, which meant most of the lesson passed before the class touched anything. The hacks now sit directly under the examples they check, and the Homework Hack lost its code runner because it is meant to be done at home in the student’s own notebook. Added the required submission frontmatter, which differs from lesson frontmatter, and a run-of-show table in section 4.

Revision 3 — topic changed to 3.6 Conditionals. Another team in 4th period was already building a Nested Conditionals lesson, and both of ours were claiming the same lesson_topic and categories, so the lessons index treated them as one slot. We talked to them, they are keeping 3.07 Nested Conditionals, and we moved down a topic to 3.6 Conditionals. Our old nested-conditionals lesson is deleted in the same pull request as this file is added, so the Nested-Conditionals topic is theirs alone.

That turned out to be more than a rename. 3.7 handed students their Booleans already decided (asks_for_money = False); 3.6 is where the Boolean gets built out of a comparison, which we had never taught. The lesson gained a whole opening section on comparison operators, and Popcorn Hack 2 changed from a nested-guard ordering bug to an elif chain ordering bug — the same idea at this topic’s difficulty, and a failure mode that counting answers cannot detect. and / or / not are used but deliberately not taught here, with a pointer to 3.5 Booleans; the section on where and runs out points forward to 4th period’s nested lesson.

8. Feedback Evidence

Feedback round 1. Watching another team’s lesson get reviewed, two problems came up that our draft shared. The examples jumped between unrelated stories, so each one spent its first thirty seconds explaining a new situation instead of teaching. And a lesson should show at least one example in JavaScript and College Board pseudocode, not Python alone. We were also reminded that examples are supposed to be themed to our own capstone project.

Feedback round 2. After the first lessons were taught, the class got a written list of what had gone wrong across all of them: popcorn hacks need to happen during teaching time, people were talking too long without understanding checks, popcorn hacks must be interactive and built into the lesson or they are just homework hacks, homework hacks should not be interactive, students are responsible for transferring popcorn hacks into their own notebooks, and the submission frontmatter from the Java Variables lesson is required and differs from lesson frontmatter. All of it applied to our draft.

Feedback round 3 — the collision. A team in 4th period reported that our lesson had written over their work. It had: our file and theirs used different permalinks but identical lesson_topic: Nested-Conditionals and categories: [Python, Nested-Conditionals], and the lessons index groups on those, so two lessons were competing for one slot. We were asked to work it out so both could coexist. We did — they keep Nested Conditionals, we moved to Conditionals, our old file is deleted in this pull request, and this lesson links to theirs at the two points where a student would naturally want it.

9. References

College Board. AP Computer Science Principles course and exam description, Big Idea 3, Topic 3.6 Conditionals, learning objective AAP-2.H. https://apcentral.collegeboard.org/media/pdf/ap-computer-science-principles-course-and-exam-description.pdf

College Board. AP CSP Exam Reference Sheet — IF / ELSE blocks, <- assignment, = equality, DISPLAY. https://apcentral.collegeboard.org/media/pdf/ap-computer-science-principles-exam-reference-sheet.pdf

The Python Language Reference, section 8.1, “The if statement.” https://docs.python.org/3/reference/compound_stmts.html#the-if-statement

“It selects exactly one of the suites by evaluating the expressions one by one until one is found to be true; then that suite is executed (and no other part of the if statement is executed or evaluated). If all expressions are false, the suite of the else clause, if present, is executed.”

Two phrases in there are this whole lesson. “one by one until one is found to be true” is why the order of an elif chain decides which branches can ever run. “if present” is why a missing else is silent rather than an error.

MDN Web Docs, “if…else.” https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/if...else

Open Coding Society. 1.02 Variables and Data Types (CSA Unit 1). https://pages.opencodingsociety.com/csa/unit_01/1_2 — the seven-stage lesson structure and the required submission frontmatter here follow that lesson.

Open Coding Society. 3.07 Nested Conditionals (4th period). https://pages.opencodingsociety.com/python/nested-conditionals/student-life — the next topic, and the lesson this one hands off to.

The Empathize section quotes the 2025-2026 CSP lesson for this topic by team Codemaxxers, which opened with a conditional that had no else branch.

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