Coding classes in Barranco, Lima

Peruvian school does not teach programming as a subject: no area of the CNEB plans of study covers it, and the curriculum treats digital skills as a competency spread across all subjects. Children who want to code learn it outside school, which is where we come in. Spanish-speaking parents planning the summer can read our guide to vacaciones útiles de programación en Barranco, about creative coding in January and February. Adults returning to learning after an office course can read, in Spanish, clases de programación en Barranco.

picture = [
    "##....#",
    "##...#.",
    "....#..",
    "..##...",
    "..##..#",
]
STEPS = [(-1, 0), (1, 0), (0, -1), (0, 1)]

def count_shapes(rows, steps):
    seen = set()
    shapes = []
    for r in range(len(rows)):
        for c in range(len(rows[0])):
            if rows[r][c] == "#" and (r, c) not in seen:
                size = 0
                stack = [(r, c)]
                seen.add((r, c))
                while stack:
                    y, x = stack.pop()
                    size += 1
                    for dy, dx in steps:
                        ny, nx = y + dy, x + dx
                        if (0 <= ny < len(rows) and 0 <= nx < len(rows[0])
                                and rows[ny][nx] == "#" and (ny, nx) not in seen):
                            seen.add((ny, nx))
                            stack.append((ny, nx))
                shapes.append(size)
    return shapes

print("Four directions:", count_shapes(picture, STEPS))

Six shapes, not three. The fill can only move up, down, left or right, so the diagonal line falls apart into three single squares, and none of them can reach the lower block. Nothing is broken in the code; it answered a different question from the one the artist asked. The fix is to say what touching means.

# picture, STEPS and count_shapes() as in Version 1
DIAGONALS = STEPS + [(-1, -1), (-1, 1), (1, -1), (1, 1)]
print("Four directions:", count_shapes(picture, STEPS))
print("Eight directions:", count_shapes(picture, DIAGONALS))
print("Squares painted:", sum(count_shapes(picture, STEPS)), sum(count_shapes(picture, DIAGONALS)))

With eight directions, corners count as touching. The diagonal joins up and links to the lower block, giving one shape of seven squares, and the count matches the artist's three. The last line is the check every learner should write: whichever rule we use, all 12 filled squares are painted exactly once. Only the grouping changes.

Real paint programs choose deliberately. Many fill with four directions, because otherwise colour leaks through a diagonal line meant as a border; the same choice appears in maps, games and medical images. There is no universally right answer, only a rule you have to state. That is the lesson: before you count shapes, decide what makes two pieces one.

1. Ages 6 to 8, with crayons. Colour some squares on squared paper. Ask a friend how many shapes there are. Do you agree about the squares that only touch at a corner?
2. Ages 9 to 11, in Scratch. Draw a maze with the pen, and make a sprite that can only move up, down, left and right. Can it squeeze between two walls that meet at a corner?
3. Ages 12 to 14, in Python. Change the picture so that four directions and eight directions give the same count. What did you have to remove?
4. Ages 15 and over. Rewrite the fill as a recursive function, then try it on a 200 by 200 picture that is entirely filled. Explain, in English, why Python complains, and why the stack version does not.

Clock rules: tz database entries for America/Lima and Asia/Kolkata; Peru last changed its clocks in 1994. The conversions are ours and hold on every date.

Book on your own clock and the mentor sees the India time. The Peruvian school calendar starts in March, when MINEDU reported 53,631 schools reopening for 6,225,000 pupils on 16 March 2026, to December; our classes run through all of it, and through the summer holidays, unless you pause them.