Unit 1: Welcome to Programming

A program is not the text you type into an editor. It is a set of instructions that must survive a chain:

idea -> source code -> saved file -> Python interpreter -> execution -> observable output

This Unit is about making that chain visible.

The first problem to solve

You will write tiny programs on purpose. The goal is not to build something impressive yet. The goal is to know exactly which layer changed when the output changed.

You will compare strings with expressions, meet the interpreter, make controlled edits, deliberately break a program, read the failure, repair it, and explain why the repaired version works.

A useful beginner habit starts here:

Do not guess what the computer probably did. Produce evidence of what it actually did.

What counts as completion

By the end of the Unit, keep one small program that you can explain line by line. Your evidence should include the source, the command or runner used to execute it, expected output, observed output, and one controlled failure/repair.

That becomes your first Code Defense. It is intentionally small. If you cannot explain a five-line program, making it fifty lines will not help.

When that evidence is complete, move to Unit 2 and inspect the environment around the code.