9.1.6 Checkerboard V1 Codehs May 2026

CodeHS Exercise 9.1.6: Checkerboard, v1 , the primary goal is to create a 2D list (a "grid") representing a checkers board using 1s for pieces and 0s for empty squares. Exercise Objectives Grid Initialization

: Create an 8x8 grid (list of lists) representing a game board. Specific Pattern top 3 rows bottom 3 rows should contain 1s. middle 2 rows should contain only 0s. Output Requirement : Use a provided print_board function to display the grid in a human-readable format. Key Logical Steps Initialize the Board : Create an empty list, typically named Fill the Top Rows

: Use a loop to append three rows, each containing eight 1s. Fill the Middle Rows : Append two rows of eight 0s. Fill the Bottom Rows : Append another three rows of eight 1s. Function Call : Pass the completed list to the print_board Common Implementation Strategies Simple Append board.append([1] * 8)

within loops is the most straightforward method for version 1. Nested Loops

: Some variations or autograders may require initializing the board with 0s first and then using nested loops to selectively assign to specific indices (e.g., board[i][j] = 1 Autograder Requirements : To pass all tests on , ensure you are using assignment statements 9.1.6 checkerboard v1 codehs

if the prompt specifically requests them, as simply printing the pattern without storing it in a grid may cause errors. Typical Pitfalls Incorrect Function Placement : Defining the print_board function inside another block or incorrectly indenting it. Missing Middle Rows

: Forgetting that the middle two rows (index 3 and 4 in an 8-row grid) must remain empty (0s). Bypassing Assignment

: Attempting to print the pattern directly instead of modifying the elements within a list structure. specific Python code

for these requirements, or are you looking for the logic behind Checkerboard v2 CodeHS Exercise 9

Common student mistakes and debugging tips

5. Implementation (JavaScript for CodeHS Karel)

function start() 


// Fill the current row starting with beeper presence based on row parity
function fillRow() 
// Determine if first cell should have a beeper
// For row 1: have beeper, row 2: no beeper, etc.
// We check if we are on a beeper to decide pattern
var startWithBeeper = beepersPresent();


while (frontIsClear()) 
    move();
    if (startWithBeeper) 
        // Alternate pattern: after moving, we want opposite
        // Better approach: move, then if column index is even/odd
        // But simpler: use a counter

However, a more reliable approach:

function start() 
    var row = 1;
    while (true) 
        // Determine if row starts with beeper
        var startWithBeeper = (row % 2 == 1);

    // Fill the row
    var col = 1;
    while (true) 
        if (startWithBeeper) 
            if (col % 2 == 1) 
                putBeeper();
else 
            if (col % 2 == 0) 
                putBeeper();
if (frontIsClear()) 
            move();
            col++;
         else 
            break;
// Move to next row
    if (facingEast()) 
        if (leftIsClear()) 
            turnLeft();
            move();
            turnLeft();
            row++;
         else 
            break;
// Optional: return to start
turnAround();
while (frontIsClear()) 
    move();
turnAround();

Simplified and cleaner version (recommended for CodeHS submission): if (frontIsClear()) move()

function start() 
    // Create checkerboard pattern
    var row = 1;
    while (true) 
        for (var i = 0; i < 100; i++)  // max columns
            if (row % 2 == 1) 
                if (i % 2 == 0) putBeeper();
             else 
                if (i % 2 == 1) putBeeper();
if (frontIsClear()) move();
            else break;

    // Go to next row
    if (leftIsClear()) 
        turnLeft();
        move();
        turnLeft();
        row++;
     else 
        break;

Informative feature: "9.1.6 checkerboard v1 (CodeHS)"

Key Requirements: