Week 02 · Wednesday: Loops (Code Crew G3)

Wednesday: Loop Code

Rocket types a short program for Nova. "Repeat five times, say hi," he reads. Nova says hi five times, then stops.

"What do you notice about the number?" Raven asks. "It tells Nova how many times."

Next, Rocket puts a loop inside a loop. Some loops even run until something happens.

Let's read each loop and count what it does.

Computers write loops in short code. Read the pseudocode below:

REPEAT 5 TIMES:
    print 'Hi!'

Answer:

WHY THIS EXERCISECSTA 1A-AP-10: A REPEAT N TIMES loop runs its body exactly N times, no more, no less.

REPEAT 3 TIMES:
    clap
    stomp

Claps:

Stomps:

REPEAT 4 TIMES:
    REPEAT 2 TIMES:
        jump

Total jumps:

WHY THIS EXERCISENested loops multiply: outer × inner. Programmers use this for grids, animations, and repeated work.

Some loops don't know how many times. They just go UNTIL something happens. Read this:

REPEAT UNTIL the cup is full:
    pour 1 spoon of water

If the cup holds 8 spoons, how many times does this loop run?

(a) 1 (b) 8 (c) Forever

My answer:

WHY THIS EXERCISEREPEAT UNTIL exits when its condition becomes true. Loops that don't have a stopping condition are bugs.

Now write a REPEAT UNTIL loop for filling a backpack with books until it is heavy.

REPEAT UNTIL ____________________________:

______________________________________

LOOP CODE CHECK

REPEAT 2 TIMES: print Hi. How many Hi lines?

REPEAT 3 TIMES: (REPEAT 3 TIMES: jump). How many jumps?

REPEAT UNTIL the box is empty: take out one toy. The box has 5 toys. How many laps?

Which loop knows its count before it starts?

When is REPEAT N TIMES the better loop to use?When is REPEAT UNTIL the better loop to use?