Because printing a 2D list can sometimes look clunky in the console, CodeHS provides a specific list comprehension line to ensure your grid prints neatly as rows and columns. However, the core of the problem lies in the of the checkerboard itself. The Secret Formula: The Modulo Operator

A function that puts down balls in alternating spaces until Karel hits a wall.

Before diving into the code, you must understand exactly what CodeHS requires for the v1 checkerboard. Karel starts at the bottom-left corner (Street 1, Avenue 1) facing East. Your program must paint the world in an alternating grid pattern. Key Constraints and Rules

while row_count > 0: # Column Counter col_count = 8

For Karel-based versions, the robot must move across the grid while painting alternating colors:

Because Karel weaves back and forth (East to West, then West to East), you need two distinct transition functions. javascript

If the sum of the row and column is (i + j = odd), you place a 0.

Many students try to use (i + j) % 2 to create a "true" alternating checkerboard pattern. While that is how real checkers look, specifically asks for solid blocks of 1s at the top and bottom with a gap in the middle.

: We start by creating a list called grid . By looping 8 times and appending a list of eight 0 s each time, we build a 2D structure (8x8).

: Instead of wrapping back to the left wall every time, Karel moves across the board in a zigzag pattern (East-to-West, then West-to-East), which vastly reduces the total line count of your code.

function drawRow() while (frontIsClear()) putBall(); safeMove(); safeMove(); // Handle the final fencepost space if necessary Use code with caution.

Which or flavor you are using (Java, JavaScript, or Karel)

To get your code fixed and working in the CodeHS editor, you need to use to traverse the grid. The outer loop manages the rows, and the inner loop manages the columns within each row.

function transitionToWest() turnLeft(); if (frontIsClear()) move(); turnLeft(); Use code with caution. javascript