15-minute session: read for 3 minutes, trace for 3, experiment for 7, and complete the check for 2. Spend longer whenever you need.
A collection stores related values. The loop visits 1, 2, and 3, updating the total from 0 to 1, then 3, then 6. Record this trace rather than guessing. Identify the first and last valid positions in this language: Pascal can declare a 1-based array, while many other examples use zero-based containers. Add another value and update the bounds correctly. Explain what an empty collection should produce.
fn main is the entry point. let introduces a binding; mut permits reassignment. println! is a macro. A reference such as &plan borrows rather than transfers ownership.
fn main() {
let minutes = [1, 2, 3];
let mut total = 0;
for value in minutes { total += value; }
println!("{}", total);
}
Expected result: 6
Keep three notes: your prediction, the actual result, and why they match or differ. The completion check grades understanding; the practice task builds skill.